The document presents Kathryn Peiman's PhD research which aims to test whether two species of vireos (Thick-billed vireo and White-eyed vireo) experience competition when they coexist in the non-breeding season by comparing locations where they occur alone or together and finding evidence of interference competition through aggression levels, exploitative competition through divergent diets, and physiological costs shown by higher stress hormone levels and lower body mass in areas of coexistence. The research was conducted in the Bahamas and Mexico during the fall and winter months and used observational methods like mapping territories and playback experiments, as well as collecting biological samples to analyze
Kathryn Peiman's research studied the effects of interspecific competition between the Thick-billed Vireo and the White-eyed Vireo during their non-breeding season in the Bahamas and Mexico by comparing locations where the species coexist to where they are found alone, finding that both species experienced higher stress levels, less diverged diets, and overlapping territories when coexisting that negatively impacted their body mass and condition.
This study examined potential competition between two species of vireos, the thick-billed vireo (TBVI) and the white-eyed vireo (WEVI), during the non-breeding season in the Bahamas and Mexico. The researcher tested for interference competition by observing territorial responses, exploitative competition by analyzing diets using stable isotopes, and physiological costs of coexistence by measuring stress hormones and body mass. Results showed that TBVI was more aggressive towards WEVI, yet their territories overlapped. WEVI consumed higher trophic level foods in sympatry. Both species had higher stress levels in sympatry, and TBVI lost body mass with declining resources. This provides evidence that both
GOOD COPY individual paper, St. Andrews Field CourseRachel Brodie
This document summarizes an experiment that examined the effects of predator interactions between green crabs and dogwhelks on the consumption of blue mussel prey. The experiment tested single-predator treatments of just dogwhelks or just crabs, as well as a multiple-predator treatment with both species present. Results showed that dogwhelk feeding rates decreased significantly in the presence of green crabs, while crab foraging increased when dogwhelks were present. Additionally, significantly more total mussels were consumed in the multiple-predator treatment than in the single-predator treatments. This indicates that the presence of another predator species impacts the feeding behavior and rates of these invertebrate predators.
Black soldier fly larvae were fed one of three types of manure (poultry, swine, bovine) or a control diet at different rates to evaluate their life history traits and ability to reduce dry matter. Larvae fed manure grew more slowly than those fed the control diet but were still able to develop. Larvae fed more of any manure type grew larger and developed faster than those fed less. All manure types supported larval development, demonstrating black soldier flies' potential for waste management while producing biomass.
Ecological Stoichiometry: The Consumer Connection: Matt WhalenNoam Ross
The document discusses how ecological stoichiometry can provide insights into consumption in food webs. It summarizes several studies that show:
1) Consumer growth rates respond unimodally to phosphorus levels in their diet, with low-phosphorus diets limiting growth.
2) Generalist herbivores may consume more low-quality, low-phosphorus foods to meet their stoichiometric needs rather than switching to more nutritious options.
3) Both generalists and specialists can balance their diets by modifying intake of different quality foods to reach their fitness and compositional targets.
This study examined the relationship between social dominance rank, stress levels, and reproductive success in female yellow-bellied marmots. The researchers found that high-ranking females had lower stress hormone levels and larger litters. However, females with the highest stress levels were more likely to successfully wean a litter. Body condition, as measured by previous year's mass, was also positively associated with breeding and weaning larger litters. Thus, while low-ranking females likely experienced more social stress, elevated stress levels did not seem to suppress reproduction in this species where females only have one chance to reproduce each year.
This article examines how non-vocal white-bellied copper-striped skinks respond to playbacks of predator vocalizations, heterospecific alarm calls, and non-alarm social vocalizations. The skinks reduced looking and increased bloating in response to alarm calls from red-vented bulbuls, but did not significantly respond to social calls from bulbuls or vocalizations from potential predators. This suggests that as non-vocal lizards, skinks likely rely on heterospecific alarm calls for information about predator presence and location.
Small differences in collection site, only 15 meters apart, resulted in large differences in the palatability of macroalgal species to herbivorous fish. An experiment found that consumption of Sargassum mangarevense collected from the intertidal reef was nearly six times greater than conspecifics collected from the adjacent subtidal reef. Similarly, intraspecific palatability of Padina boryana appeared to vary between collection sites, though the difference was not statistically significant. This demonstrates that algal palatability can vary substantially over very small spatial scales, and researchers should carefully consider collection locations when setting up herbivory experiments.
Kathryn Peiman's research studied the effects of interspecific competition between the Thick-billed Vireo and the White-eyed Vireo during their non-breeding season in the Bahamas and Mexico by comparing locations where the species coexist to where they are found alone, finding that both species experienced higher stress levels, less diverged diets, and overlapping territories when coexisting that negatively impacted their body mass and condition.
This study examined potential competition between two species of vireos, the thick-billed vireo (TBVI) and the white-eyed vireo (WEVI), during the non-breeding season in the Bahamas and Mexico. The researcher tested for interference competition by observing territorial responses, exploitative competition by analyzing diets using stable isotopes, and physiological costs of coexistence by measuring stress hormones and body mass. Results showed that TBVI was more aggressive towards WEVI, yet their territories overlapped. WEVI consumed higher trophic level foods in sympatry. Both species had higher stress levels in sympatry, and TBVI lost body mass with declining resources. This provides evidence that both
GOOD COPY individual paper, St. Andrews Field CourseRachel Brodie
This document summarizes an experiment that examined the effects of predator interactions between green crabs and dogwhelks on the consumption of blue mussel prey. The experiment tested single-predator treatments of just dogwhelks or just crabs, as well as a multiple-predator treatment with both species present. Results showed that dogwhelk feeding rates decreased significantly in the presence of green crabs, while crab foraging increased when dogwhelks were present. Additionally, significantly more total mussels were consumed in the multiple-predator treatment than in the single-predator treatments. This indicates that the presence of another predator species impacts the feeding behavior and rates of these invertebrate predators.
Black soldier fly larvae were fed one of three types of manure (poultry, swine, bovine) or a control diet at different rates to evaluate their life history traits and ability to reduce dry matter. Larvae fed manure grew more slowly than those fed the control diet but were still able to develop. Larvae fed more of any manure type grew larger and developed faster than those fed less. All manure types supported larval development, demonstrating black soldier flies' potential for waste management while producing biomass.
Ecological Stoichiometry: The Consumer Connection: Matt WhalenNoam Ross
The document discusses how ecological stoichiometry can provide insights into consumption in food webs. It summarizes several studies that show:
1) Consumer growth rates respond unimodally to phosphorus levels in their diet, with low-phosphorus diets limiting growth.
2) Generalist herbivores may consume more low-quality, low-phosphorus foods to meet their stoichiometric needs rather than switching to more nutritious options.
3) Both generalists and specialists can balance their diets by modifying intake of different quality foods to reach their fitness and compositional targets.
This study examined the relationship between social dominance rank, stress levels, and reproductive success in female yellow-bellied marmots. The researchers found that high-ranking females had lower stress hormone levels and larger litters. However, females with the highest stress levels were more likely to successfully wean a litter. Body condition, as measured by previous year's mass, was also positively associated with breeding and weaning larger litters. Thus, while low-ranking females likely experienced more social stress, elevated stress levels did not seem to suppress reproduction in this species where females only have one chance to reproduce each year.
This article examines how non-vocal white-bellied copper-striped skinks respond to playbacks of predator vocalizations, heterospecific alarm calls, and non-alarm social vocalizations. The skinks reduced looking and increased bloating in response to alarm calls from red-vented bulbuls, but did not significantly respond to social calls from bulbuls or vocalizations from potential predators. This suggests that as non-vocal lizards, skinks likely rely on heterospecific alarm calls for information about predator presence and location.
Small differences in collection site, only 15 meters apart, resulted in large differences in the palatability of macroalgal species to herbivorous fish. An experiment found that consumption of Sargassum mangarevense collected from the intertidal reef was nearly six times greater than conspecifics collected from the adjacent subtidal reef. Similarly, intraspecific palatability of Padina boryana appeared to vary between collection sites, though the difference was not statistically significant. This demonstrates that algal palatability can vary substantially over very small spatial scales, and researchers should carefully consider collection locations when setting up herbivory experiments.
The Dodo was a flightless bird that was endemic to the island of Mauritius. It stood about 1 meter tall and weighed between 10-18 kg. Its exact appearance is uncertain as it is only known from 17th century drawings, paintings, and accounts. It is believed to have had brownish-grey plumage, yellow feet, a tufted tail, and a grey naked head with a black, yellow, and green beak. It became extinct in the late 17th century due to hunting and destruction of habitat by humans and invasive species. One account from 1598 provides a description of the Dodo.
This research article summarizes two field experiments that investigated how foraging decisions in the tropical lizard Anolis cristatellus are shaped by various ecological factors. In Experiment 1, lizards foraged faster when food was scarce and other lizards were present, while they took longer to feed when food was abundant and no conspecifics were present. Experiment 2 found that lizards took longer to feed and used intermediate perches more when the feeding tray was farther away, indicating they incorporated perceived predation risk into decisions. Overall, the results suggest A. cristatellus integrates information about food availability, conspecific activity, and predation risk to adjust foraging behavior.
presentation contain different type of interactions, competition-intra and inter-specific, mechanism of competition-Exploitation and Interference, Mathematical models of Competition i.e. Hutchinson Ratio, Exponential Growth, Logistic Model, Lotka-Volterra Competition Model, Tilman's Resource Model, Results of Competition i.e. Range restriction, Competitive Displacement, Competitive Exclusion , Competitive Displacement Hypothesis, Ecological Niche, Evolution of new species, Factors Affecting Competition, Case studies
This study investigated lateralization in feeding behaviors and foot scratching preferences in captive Caribbean flamingos, and whether these behaviors were related to pair-bonding and aggression. The study found that 4 birds displayed individual preferences in one of the two feeding behaviors. Foot scratching preference was related to age, with older birds preferring their right foot. Birds that scratched with their left foot were more likely to be involved in and lose fights. However, no significant lateralization was found in foot scratching. The lateral feeding behaviors did not appear related to social cohesion.
This document discusses limiting factors that determine the carrying capacity of an environment for a species. It identifies factors that are density dependent, meaning they strongly affect populations when density reaches a certain level, such as competition for resources, predator-prey relationships, herbivore effects, and parasitism and disease. It also identifies density-independent factors that affect populations regardless of size or density, such as hurricanes, droughts, and wildfires. Examples are provided to illustrate both types of limiting factors.
1) The document describes experiments measuring boldness and foraging behaviors in two species of crayfish, O. rusticus and O. propinquus.
2) Three measures of boldness were taken for each crayfish - aggression towards a novel object, latency to exit a refuge in a novel environment, and giving-up density in foraging.
3) The experiments aimed to determine if behaviors were consistent within individuals over time and across contexts, and how individual variation related to foraging behaviors.
Selection pressure refers to factors in an organism's environment that give certain variations an advantage, pushing evolution in a direction. Random mutations occur during reproduction, and favorable mutations that increase survival and reproduction will become more common through natural selection over generations. A selection pressure can be anything consistent that impacts survival and reproduction rates, like availability of resources, presence of predators, or competition. Selection operates at the individual level, favoring traits that increase individual fitness even if they harm the species as a whole.
This study investigated the effects of habitat restoration in 12 urban parks in Metro Vancouver on plant and pollinator communities. Restored plots had higher plant species richness and diversity compared to control plots, but similar plant abundance. Pollinator abundance, richness and diversity were not significantly different between restored and control plots. Network analysis found control plots had higher asymmetry, suggesting invasive plants increase network resilience. The results suggest that while restorations improved plant diversity, added native plants did not provide enough additional floral resources to significantly change pollinator communities compared to resources from invasive species in control plots. Managers should ensure alternative forage is available after invasive removal by planting generalist native species with overlapping blooms.
Species interactions such as competition, predation, and symbiosis influence natural selection by affecting population sizes and survival/reproductive rates. These interactions are a major factor in determining which traits become more common or rare in a population over generations as organisms adapt to each other.
Impact of Environment on Loss of Genetic Diversity and Speciation
Genetic variation describes naturally occurring genetic differences among individuals of the same species. This variation permits flexibility and survival of a population in the face of changing environmental circumstances. Consequently, genetic variation is often considered an advantage, as it is a form of preparation for the unexpected. But how does genetic variation increase or decrease? And what effect do fluctuations in genetic variation have on populations over time?
This document discusses animal competition through a group presentation on the topic. It begins by defining competition as a negative interaction that occurs when organisms require the same limited resources. It then discusses what organisms compete for (air, water, food, space), types of competition (interference and exploitative), and ways organisms avoid competition (geographic isolation, mechanical isolation, behavioral isolation, foraging differences). The document provides examples for each topic and concludes by stating competition acts as a regulator.
Natural selection is the driving force behind evolution. According to Charles Darwin's theory of natural selection:
1) There is genetic variation within populations. Traits that increase reproductive success will be passed on more frequently.
2) Individuals with traits better suited to the environment will have greater access to resources and be more likely to reproduce.
3) Over time, individuals with traits that increase reproductive success will comprise a greater proportion of the population, leading populations to evolve.
Behavioral traits can change more quickly than morphology in response to environmental cues, allowing behaviors to lead evolutionary changes. A behavioral shift can occur faster than an adaptive change in physiology, taking the lead in evolution. While behaviors are flexible, they can also inhibit evolutionary changes by preventing natural selection from acting on other traits when environments change. A unified framework is needed to understand how behaviors can both drive and inhibit evolutionary processes through altering selection pressures.
This document discusses competition between ecological populations. It defines competition and describes different types, including intraspecific and interspecific competition. Mechanisms of competition include interference and exploitative competition. The effects of competition can include changes to population size, spatial dispersion, phenotypes, and biodiversity. Competition can be studied through models, observations, and experiments. The competitive exclusion principle and niche differentiation are introduced as ways that species can coexist by reducing competitive interactions. Character displacement is given as an example of niche differentiation. The document then discusses a case study on competition between insectivorous bat species in Malaysia.
This study examined ecological resource partitioning and relative fitness between two closely related songbird species, Swamp Sparrows and Song Sparrows, that co-occur in sympatry. The study addressed three questions: 1) Do the species use nest sites non-randomly based on microhabitat features? 2) Do nest site microhabitats differ between the species? 3) Are there fitness consequences for using nest sites more similar to the other species? The study found that both species used nest sites non-randomly based on microhabitat. Nest sites also differed between species, with Swamp Sparrows preferring sites with more water and aquatic vegetation. Surprisingly, Song Sparrows had greater reproductive success when using nest sites more
The Whittier College ENVS 396 class sampled arthropods in Zuma Canyon using pitfall traps placed in restored, native, and invaded sites. The invaded site had the greatest number and species richness of arthropods, while the native site had the highest diversity. Restored and native sites did not significantly differ in species richness as hypothesized. However, species richness was highest in the invaded site rather than the native site as predicted.
Understanding the basic principles of population genetics and its applicationAlexander Decker
This document discusses key concepts in population genetics, including:
- Gene pool, gene frequency, genetic equilibrium, genetic drift, natural selection, isolation
- Hardy-Weinberg principle, which states that gene frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences
- How Hardy and Weinberg used Punnett squares and equations to mathematically prove the principle based on observations of dominant and recessive alleles in a population
- An example application of using the Hardy-Weinberg equation to determine the number of heterozygotes and homozygous individuals for a dominant trait in a population
1) Volunteers used different types of plastic cutlery ("appendages") to collect food in grass and tarmac habitats over generations to study microevolution in small populations.
2) In the grass habitat, the spoon appendage became fixed within 3 generations on average, suggesting it was best adapted, while in tarmac no adaptation was seen.
3) The study demonstrates how strong selection can drive rapid evolution in small populations over just a few generations, though human subjects and small sample sizes limit conclusions that can be drawn.
Mutualism describes an interaction that benefits both species. A well-known example exists in the mutualistic relationship between alga and fungus that form lichens. The photosynthesizing alga supplies the fungus with nutrients and gains protection in return. The relationship also allows lichen to colonize habitats inhospitable to either organism alone. In rare cases, mutualistic partners cheat. Some bees and birds receive food rewards without providing pollination services in exchange. These "nectar robbers" chew a hole at the base of the flower and miss contact with the reproductive structures.
Both species involved in the interaction are benefited. These interactions take place in three patterns:
Facultative mutualism – Species survive on their own under favorable conditions
Obligate mutualism – One species is dependent for survival on the other
Diffusive mutualism – One entity can live with multiple partners
These relationships have three purposes:
Defensive mutualism
Trophic mutualism
Dispersive mutualism
This document discusses key concepts in biological communities and species interactions, including critical environmental factors, adaptation, natural selection, speciation, ecological niches, population dynamics, community properties, succession, and introduced species. Species distributions are determined by critical environmental factors, and adaptation and natural selection lead to changes in populations over time. Isolation can cause speciation, while species interactions like competition, predation, and mutualism influence community structure. Communities change over time through succession and can be impacted by introduced species.
- Biotic interactions include predator-prey relationships, plant-herbivore relationships, competition, and symbiosis. Abiotic interactions involve interactions between organisms and environmental factors like temperature, light, and nutrients.
- Density-dependent factors like predation and competition cause populations to decrease when densities are high and increase when densities are low. Density-independent factors like fires and floods impact populations independently of their densities.
- Predator-prey relationships can follow stable, cyclical, erratic, or extinction patterns depending on factors like carrying capacity and reproduction rates of both species. Predators benefit from food while prey benefit from reduced competition.
The Dodo was a flightless bird that was endemic to the island of Mauritius. It stood about 1 meter tall and weighed between 10-18 kg. Its exact appearance is uncertain as it is only known from 17th century drawings, paintings, and accounts. It is believed to have had brownish-grey plumage, yellow feet, a tufted tail, and a grey naked head with a black, yellow, and green beak. It became extinct in the late 17th century due to hunting and destruction of habitat by humans and invasive species. One account from 1598 provides a description of the Dodo.
This research article summarizes two field experiments that investigated how foraging decisions in the tropical lizard Anolis cristatellus are shaped by various ecological factors. In Experiment 1, lizards foraged faster when food was scarce and other lizards were present, while they took longer to feed when food was abundant and no conspecifics were present. Experiment 2 found that lizards took longer to feed and used intermediate perches more when the feeding tray was farther away, indicating they incorporated perceived predation risk into decisions. Overall, the results suggest A. cristatellus integrates information about food availability, conspecific activity, and predation risk to adjust foraging behavior.
presentation contain different type of interactions, competition-intra and inter-specific, mechanism of competition-Exploitation and Interference, Mathematical models of Competition i.e. Hutchinson Ratio, Exponential Growth, Logistic Model, Lotka-Volterra Competition Model, Tilman's Resource Model, Results of Competition i.e. Range restriction, Competitive Displacement, Competitive Exclusion , Competitive Displacement Hypothesis, Ecological Niche, Evolution of new species, Factors Affecting Competition, Case studies
This study investigated lateralization in feeding behaviors and foot scratching preferences in captive Caribbean flamingos, and whether these behaviors were related to pair-bonding and aggression. The study found that 4 birds displayed individual preferences in one of the two feeding behaviors. Foot scratching preference was related to age, with older birds preferring their right foot. Birds that scratched with their left foot were more likely to be involved in and lose fights. However, no significant lateralization was found in foot scratching. The lateral feeding behaviors did not appear related to social cohesion.
This document discusses limiting factors that determine the carrying capacity of an environment for a species. It identifies factors that are density dependent, meaning they strongly affect populations when density reaches a certain level, such as competition for resources, predator-prey relationships, herbivore effects, and parasitism and disease. It also identifies density-independent factors that affect populations regardless of size or density, such as hurricanes, droughts, and wildfires. Examples are provided to illustrate both types of limiting factors.
1) The document describes experiments measuring boldness and foraging behaviors in two species of crayfish, O. rusticus and O. propinquus.
2) Three measures of boldness were taken for each crayfish - aggression towards a novel object, latency to exit a refuge in a novel environment, and giving-up density in foraging.
3) The experiments aimed to determine if behaviors were consistent within individuals over time and across contexts, and how individual variation related to foraging behaviors.
Selection pressure refers to factors in an organism's environment that give certain variations an advantage, pushing evolution in a direction. Random mutations occur during reproduction, and favorable mutations that increase survival and reproduction will become more common through natural selection over generations. A selection pressure can be anything consistent that impacts survival and reproduction rates, like availability of resources, presence of predators, or competition. Selection operates at the individual level, favoring traits that increase individual fitness even if they harm the species as a whole.
This study investigated the effects of habitat restoration in 12 urban parks in Metro Vancouver on plant and pollinator communities. Restored plots had higher plant species richness and diversity compared to control plots, but similar plant abundance. Pollinator abundance, richness and diversity were not significantly different between restored and control plots. Network analysis found control plots had higher asymmetry, suggesting invasive plants increase network resilience. The results suggest that while restorations improved plant diversity, added native plants did not provide enough additional floral resources to significantly change pollinator communities compared to resources from invasive species in control plots. Managers should ensure alternative forage is available after invasive removal by planting generalist native species with overlapping blooms.
Species interactions such as competition, predation, and symbiosis influence natural selection by affecting population sizes and survival/reproductive rates. These interactions are a major factor in determining which traits become more common or rare in a population over generations as organisms adapt to each other.
Impact of Environment on Loss of Genetic Diversity and Speciation
Genetic variation describes naturally occurring genetic differences among individuals of the same species. This variation permits flexibility and survival of a population in the face of changing environmental circumstances. Consequently, genetic variation is often considered an advantage, as it is a form of preparation for the unexpected. But how does genetic variation increase or decrease? And what effect do fluctuations in genetic variation have on populations over time?
This document discusses animal competition through a group presentation on the topic. It begins by defining competition as a negative interaction that occurs when organisms require the same limited resources. It then discusses what organisms compete for (air, water, food, space), types of competition (interference and exploitative), and ways organisms avoid competition (geographic isolation, mechanical isolation, behavioral isolation, foraging differences). The document provides examples for each topic and concludes by stating competition acts as a regulator.
Natural selection is the driving force behind evolution. According to Charles Darwin's theory of natural selection:
1) There is genetic variation within populations. Traits that increase reproductive success will be passed on more frequently.
2) Individuals with traits better suited to the environment will have greater access to resources and be more likely to reproduce.
3) Over time, individuals with traits that increase reproductive success will comprise a greater proportion of the population, leading populations to evolve.
Behavioral traits can change more quickly than morphology in response to environmental cues, allowing behaviors to lead evolutionary changes. A behavioral shift can occur faster than an adaptive change in physiology, taking the lead in evolution. While behaviors are flexible, they can also inhibit evolutionary changes by preventing natural selection from acting on other traits when environments change. A unified framework is needed to understand how behaviors can both drive and inhibit evolutionary processes through altering selection pressures.
This document discusses competition between ecological populations. It defines competition and describes different types, including intraspecific and interspecific competition. Mechanisms of competition include interference and exploitative competition. The effects of competition can include changes to population size, spatial dispersion, phenotypes, and biodiversity. Competition can be studied through models, observations, and experiments. The competitive exclusion principle and niche differentiation are introduced as ways that species can coexist by reducing competitive interactions. Character displacement is given as an example of niche differentiation. The document then discusses a case study on competition between insectivorous bat species in Malaysia.
This study examined ecological resource partitioning and relative fitness between two closely related songbird species, Swamp Sparrows and Song Sparrows, that co-occur in sympatry. The study addressed three questions: 1) Do the species use nest sites non-randomly based on microhabitat features? 2) Do nest site microhabitats differ between the species? 3) Are there fitness consequences for using nest sites more similar to the other species? The study found that both species used nest sites non-randomly based on microhabitat. Nest sites also differed between species, with Swamp Sparrows preferring sites with more water and aquatic vegetation. Surprisingly, Song Sparrows had greater reproductive success when using nest sites more
The Whittier College ENVS 396 class sampled arthropods in Zuma Canyon using pitfall traps placed in restored, native, and invaded sites. The invaded site had the greatest number and species richness of arthropods, while the native site had the highest diversity. Restored and native sites did not significantly differ in species richness as hypothesized. However, species richness was highest in the invaded site rather than the native site as predicted.
Understanding the basic principles of population genetics and its applicationAlexander Decker
This document discusses key concepts in population genetics, including:
- Gene pool, gene frequency, genetic equilibrium, genetic drift, natural selection, isolation
- Hardy-Weinberg principle, which states that gene frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences
- How Hardy and Weinberg used Punnett squares and equations to mathematically prove the principle based on observations of dominant and recessive alleles in a population
- An example application of using the Hardy-Weinberg equation to determine the number of heterozygotes and homozygous individuals for a dominant trait in a population
1) Volunteers used different types of plastic cutlery ("appendages") to collect food in grass and tarmac habitats over generations to study microevolution in small populations.
2) In the grass habitat, the spoon appendage became fixed within 3 generations on average, suggesting it was best adapted, while in tarmac no adaptation was seen.
3) The study demonstrates how strong selection can drive rapid evolution in small populations over just a few generations, though human subjects and small sample sizes limit conclusions that can be drawn.
Mutualism describes an interaction that benefits both species. A well-known example exists in the mutualistic relationship between alga and fungus that form lichens. The photosynthesizing alga supplies the fungus with nutrients and gains protection in return. The relationship also allows lichen to colonize habitats inhospitable to either organism alone. In rare cases, mutualistic partners cheat. Some bees and birds receive food rewards without providing pollination services in exchange. These "nectar robbers" chew a hole at the base of the flower and miss contact with the reproductive structures.
Both species involved in the interaction are benefited. These interactions take place in three patterns:
Facultative mutualism – Species survive on their own under favorable conditions
Obligate mutualism – One species is dependent for survival on the other
Diffusive mutualism – One entity can live with multiple partners
These relationships have three purposes:
Defensive mutualism
Trophic mutualism
Dispersive mutualism
This document discusses key concepts in biological communities and species interactions, including critical environmental factors, adaptation, natural selection, speciation, ecological niches, population dynamics, community properties, succession, and introduced species. Species distributions are determined by critical environmental factors, and adaptation and natural selection lead to changes in populations over time. Isolation can cause speciation, while species interactions like competition, predation, and mutualism influence community structure. Communities change over time through succession and can be impacted by introduced species.
- Biotic interactions include predator-prey relationships, plant-herbivore relationships, competition, and symbiosis. Abiotic interactions involve interactions between organisms and environmental factors like temperature, light, and nutrients.
- Density-dependent factors like predation and competition cause populations to decrease when densities are high and increase when densities are low. Density-independent factors like fires and floods impact populations independently of their densities.
- Predator-prey relationships can follow stable, cyclical, erratic, or extinction patterns depending on factors like carrying capacity and reproduction rates of both species. Predators benefit from food while prey benefit from reduced competition.
The document outlines several key concepts in ecology and conservation including:
1. Factors that affect the distribution of plant and animal species such as temperature, water, light, soil pH, breeding sites, and food supply.
2. Methods for measuring ecological concepts like biomass, primary production, trophic levels, and ecological succession.
3. The major biomes of the world and how abiotic factors like temperature and rainfall affect their distribution.
4. Reasons for biodiversity conservation using rainforests as an example, including ethical, ecological, economic, and aesthetic arguments. Accelerating extinction rates are threatening many species.
The document provides an overview of key concepts related to evolution, biological communities, and species interactions. It discusses evolution and natural selection, ecological niches, species interactions like competition and predation, community properties, how communities change over time through succession, and factors that influence where organisms can live.
This document discusses how species interactions such as competition, predation, and symbiosis influence population sizes and act as agents of natural selection. Competition over resources can lead to competitive exclusion where one species is better adapted to acquire resources. Predator-prey relationships are also influenced by population sizes, as changes in one population result in changes to other linked populations. These interactions drive adaptations that allow species to coexist or gain advantages.
This document discusses Darwin's theory of evolution by natural selection. It explains that organisms vary in traits, and traits that increase survival and reproduction in the current environment will be passed on to offspring, leading to evolution of new species over time as environments change. The key mechanisms are overpopulation causing competition over limited resources, variation in traits among individuals, and survival of the fittest where individuals with advantageous traits are more likely to survive and pass on those traits.
This document discusses key concepts in ecology, including:
1) Ecology is the study of interactions between organisms and their environment. It examines relationships between living and non-living components.
2) Organisms exist within different ecological levels from cells to the biosphere. Food chains and webs show how energy flows between organisms as herbivores, carnivores and omnivores feed.
3) Populations grow over time according to exponential, logistic, or S-curve models until limited by carrying capacity due to factors like predation, competition, and crowding. Human population growth poses challenges for global carrying capacity.
This document discusses key concepts of evolution through natural selection including overpopulation, variation, survival of the fittest, and the formation of new species. It explains how organisms tend to overproduce offspring leading to competition over limited resources. Individuals within a population vary in traits and advantageous variations increase the chances of survival and are passed on, known as survival of the fittest. Over time, inheritance of advantageous traits can lead to the evolution of new species through adaptive radiation.
Ecology is the scientific study of interactions between organisms and their environment. The components of ecology include abiotic (non-living) factors like temperature and biotic (living) factors like other organisms. A niche describes an organism's role and interactions within its ecosystem, including how it meets its needs. Relationships between organisms in an ecosystem can be symbiotic like mutualism, or involve one organism benefiting more than the other like parasitism or commensalism. Natural selection leads to evolution as organisms with traits better suited to their environment are more likely to survive and pass on those traits, changing the gene frequency in a population over time. Speciation occurs when reproductive isolation splits one species into two distinct species.
Living things exist in ecosystems where they can survive given local conditions like temperature and food availability. An ecosystem includes both biotic (living) and abiotic (non-living) factors. A niche describes a species' role within its habitat, including what it eats, where it lives, and its interactions with other organisms and environmental conditions.
This document discusses Jean Baptiste de Lamarck's theory of evolution, known as Lamarckism. The key points are:
1) Lamarck proposed the "theory of inheritance of acquired characters", which stated that adaptations developed in an organism's lifetime in response to environmental changes could be passed on to offspring.
2) An example given is the long neck of giraffes developing over generations from ancestral deer as they stretched their necks to reach higher tree leaves.
3) Lamarck believed evolution occurred through the inheritance of acquired traits that provided adaptations to an organism's environment and needs. This mechanism of adaptive modification drove evolutionary change.
Cape biology uni 2 -_ecosystems_population_ecology_and_practical_methods_of_e...Hilton Ritch
This document discusses methods for estimating population sizes and distributions in ecology. It explains that directly counting all individuals in a population is often impossible, so sampling techniques are used instead to estimate population parameters. Common sampling methods described include quadrat sampling, transect sampling, and mark-release-recapture. Factors that influence the accuracy of population estimates, such as sample size and randomization, are also discussed.
12 biology organism and populations yogesh kumarYogesh Pandey
Ecology is the study of interactions between organisms and their environment. It examines these interactions at four levels - organisms, populations, communities, and biomes. The major biomes in India include tropical rainforests, deciduous forests, deserts, and sea coasts. Within these biomes, populations of organisms interact through predation, competition, and parasitism. Predation involves a predator species consuming a prey species, while competition lowers the fitness of species competing for the same resources. Parasitism benefits one species through deriving food or shelter from another host species.
JJC_V. Biodiversity and Evolution, Climate and Biodiversity,.pdfJorielCruz1
This document discusses biodiversity, evolution, and the roles of species in ecosystems. It defines biodiversity as the variety of organisms within an ecosystem and notes that it depends on climatic conditions and region. Evolution occurs over generations as traits beneficial for survival and reproduction spread through natural selection. Species play different ecological roles or niches in ecosystems. Some species indicate environmental changes or shape habitats for other species. Overall biodiversity and the roles species play are important for ecosystem sustainability.
Ecosystems are composed of interacting biotic and abiotic factors. Biotic factors include species, habitats, populations, and communities. Autotrophs produce their own food through photosynthesis, while heterotrophs consume food obtained from other organisms or matter. Food chains and food webs show the transfer of energy and matter between trophic levels. As the human population increases, concentrations of greenhouse gases like carbon dioxide and methane are also increasing, intensifying the natural greenhouse effect and potentially disrupting ecosystems through impacts like rising sea levels and changes in climate and photosynthesis rates. Population growth can be described using concepts like carrying capacity, exponential growth phase, mortality, and transition phase. Evolution occurs through mechanisms like genetic variation,
The document discusses key concepts related to biodiversity including genetic diversity, species diversity, and habitat diversity. It defines biodiversity as the living diversity within an area. Genetic diversity refers to the genetic variation within a species. Species diversity is the variety of species in an area. Habitat diversity means the range of habitats or ecological niches. The document then discusses the theory of evolution by natural selection proposed by Charles Darwin, explaining how organisms adapt to their environments and reproductive isolation leads to speciation. Plate tectonics is mentioned as a factor influencing evolution and biodiversity by separating land masses and creating new habitats. Ecological succession and the impact of humans on biodiversity are also summarized.
- Hutchinson's ratio describes the size difference between similar species that coexist, typically ranging from 1:1.1 to 1:1.4. It is measured by comparing traits like body weight or lengths of feeding appendages.
- May's d/w law states that competing species can stably coexist only when their niche overlap ratio (d/w) is approximately equal to 1, where d is the difference between the means of their resource distributions and w is the standard deviation.
- Dyar's law and Przibram's law describe geometric growth patterns in insect body parts and cells between life stages. However, these laws often do not apply due to non-constant growth rates and disharmonic
The document discusses food webs and ecological pyramids. It defines ecological niches and explains trophic levels in a food chain. Primary producers are at the first trophic level, primary consumers at the second, and carnivores at the third and fourth levels. Food chains are simplified and food webs show more complex, interconnected feeding relationships in an ecosystem. Ecological pyramids illustrate the energy, numbers, and biomass at each trophic level, with higher levels containing less energy and fewer individuals than lower levels due to energy loss between trophic transfers.
The document provides an overview of key concepts in biology, including:
1) Biology is experiencing breakthroughs in fields like genetics, medicine, and ecology.
2) All living things share properties of order, growth/development, response to stimuli, and evolution.
3) Ecosystems involve interactions between organisms and their environment, with energy flowing through producers, consumers, and decomposers.
4) The diversity of life emerges from underlying genetic unity and the process of biological evolution over time.
This document discusses key concepts in ecology including the organization of ecological systems from individual organisms to the biosphere. It covers ecology at the individual, population, community, and ecosystem levels. Some topics discussed include homeostasis in individuals, population dynamics, survivorship curves, interactions among species like competition and predation, food chains and webs, energy and nutrient flows, and biogeochemical cycles. Diagrams are provided to illustrate ecological pyramids, hydrologic cycle, and carbon, nitrogen, and phosphorus cycles.
2. Complete competitors cannot coexist (Gause’s law)
-predicts that ecologically similar species will
partition resources to reduce competition
The idea is simple, but
demonstrating that interspecific
competition is currently occurring
is difficult in natural populations.
How can we tell whether current interactions are due to
competition? And how can we separate interactions over
food resources from interactions due to breeding
requirements?
3. Solution? Birds during the non-breeding season!
• no breeding requirements (only individual survival)
• compare locations of sympatry
(species coexist) to allopatry (species
found alone) to test whether they have
experienced interspecific competition
(selection for divergence only in
sympatry)
• also include ecological effects due to seasonal changes (may
change the intensity of competition)
I will test hypotheses related to three topics:
• Interference competition
• Exploitative competition
• Physiological effects of coexistence
Allopatry
Sympatry
4. TBVI (resident in the Bahamas)
Thick-billed vireo (Vireo crassirostris)
Weight: 14.1 g
Bill length: 8.83 mm
Wing chord: 61.6 mm
WEVI (breeds in south-east US;
winters in the Bahamas and
Mexico)
White-eyed vireo (Vireo griseus)
Weight: 11.9 g
Bill length: 7.45 mm
Wing chord: 60.2 mm
5. Allopatric
WEVI
Sympatric
TBVI and
WEVI Allopatric
TBVI
I visited three locations to test for evolutionary effects of
species coexistence (comparing allopatry to sympatry): Abaco
Island, the Bahamas (sympatry); San Salvador Island, the
Bahamas (allopatric TBVI); and Los Tuxtlas,
Mexico (allopatric WEVI). At each location, I
tested for the
ecological effects
of declining
resource abundance
by comparing data
collected in the fall
[Sept-Nov] to the
winter [Jan-Mar].
6. Direct interactions between individuals over a shared,
limited resource
• direct interactions can involve signalling (color,
posture, chemicals, auditory cues, etc) and fighting
(biting, attacking, striking, etc)
• types of resources include mates, offspring-rearing
locations (nests, burrows, holes, etc), predator-free
space, environmental refuges (basking sites, moisture-
rich areas), and food
-but mates are only shared if the species hybridize; offspring
locations if it is during the breeding season; predator-free space
if predation is a major selective pressure; and environmental
refuges if individuals are vulnerable to those stresses. Food,
however, is always necessary to both species.
7. Question:
Do TBVI and WEVI engage in interference
competition?
Hypotheses and predictions:
1) If heterospecific aggression is beneficial, it will
be higher in individuals from sympatry
compared to allopatry, while conspecific
aggression will not differ.
2) If the benefits of excluding individuals
outweigh the costs, territories will be mutually
exlusive.
8. Methods:
Territory holders were color-banded for individual
recognition.
I used taxidermy mounts and playback of songs/chatter
to simulate territorial intrusions.
Each bird received a 3 minute trial, 3 minutes of silence,
then a second 3 minute trial. I systematically alternated
the order of conspecific and heterospecific trials among
territory holders to control for presentation order.
I recorded the movement (time spent within 0-2m and 2-
5m of the mount, and time spent attacking the mount)
and vocal responses (number of songs and chatters) of
each territory holder.
10. Results (using GLMMs with identity link):
691 trials; 54 individual TBVI and 53 individual WEVI
responded to at least one trial.
Species differences: TBVI were much more aggressive than
WEVI (attacked and spent time closer to the mount)
(p<0.0001).
Intra vs interspecific aggression: Both species were more
aggressive to conspecifics than heterospecifics (p<0.001).
Evolutionary effects: Both conspecific and heterospecific
aggression higher in sympatry compared to allopatry for
TBVI (p=0.03); no difference for WEVI.
Ecological effects: No clear season effect.
11. Methods: I used conspecific
playback and GPS units to
map the boundary of
territory holders (TBVI:
n=49; WEVI: n=41).
Results: Conspecific
territories barely overlapped
(<10%), while heterospecific
territories had a lot of
overlap (>50%).
Example of TBVI and WEVI territories in
sympatry
12. Do TBVI and WEVI engage in interference
competition?
Yes, but it is asymmetrical and perhaps not an
adaptive response
1) Heterospecific aggression AND conspecific
aggression were higher in sympatry compared to
allopatry. Cannot conclude whether one or both
behaviors were under selection in sympatry.
2) Conspecific territories were mutually exlusive, but
heterospecific territories overlapped.
Surprisingly, the high levels of heterospecific
aggression by TBVI towards WEVI did not
result in exclusive territories.
13. Indirect interactions between individuals over a
shared, limited resource
• indirect means that individuals may never
meet or physically interact, but both consume
the same resource so there is less available for
individuals of the other species
• resource acquition involves detection (seeing
and identification), capture (handling time)
and consumption (eating it)
-Food is the most common resource shared during
exploitative competition.
14. Question:
Do TBVI and WEVI engage in exploitative
competition?
Hypotheses and predictions:
1) If resources are shared between species, diet
will diverge between individuals from
sympatry compared to allopatry.
2) If rainfall affects arthropods and fruits, then the
abundance of food will decline from fall to
winter mirroring decreases in rainfall.
15. Methods:
Clipped 2mm of claw from each
individual.
Each claw was analyzed for nitrogen stable isotopes
(δN):
-all individuals obtain their nitrogen from their food
source, and this accumulates up the food chain
-therefore, nitrogen isotopes reflect trophic level
-this can separate birds eating fruit from those
eating herbivorous insects (caterpillars, leaf
hoppers) and those eating carnivorous arthropods
(predaceous beetles, spiders)
16. Results (ANOVAs; TBVI: n=151, WEVI: n=92):
Species differences: WEVI fed higher on the food
chain than TBVI (p=0.0004).
Evolutionary and ecological effects: WEVI fed higher
on the food chain in the winter than the fall in
symptry but did not change their diet in allopatry
(p=0.002). TBVI did not
change their diet between
sympatry/allopatry or from
the fall to the winter.
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
7.50
2.50 3.50 4.50 5.50 6.50 7.50
Nitrogenstableisotopevaluesin
thewinter
Nitrogen stable isotope values in the fall
Individual TBVI were consistent in their
diet from the fall to the winter.
17. Methods:
Every 200m along trail conducted a 50m transect
perpendicular to the trail by collecting arthropods
at two sampling points: 25m and 50m.
I used beat sheets (nylon on a PVC pipe frame) to
collect all arthropods shaken from four trees at
each sampling point.
I also estimated the number of fruits on all Bursera
simaruba trees within 5m of
the 50m transect (both species
have been seen to consume
this fruit).
18. Results (repeated-measure ANOVAs; n=80
transects per season):
Ecological contrast: The number of arthropods
declined from fall to winter (p=0.017). Fruit
abundance did not change from fall to winter.
Evolutionary contrast: The decline in arthropod
abundance was stronger in sympatry than in
allopatry (p=0.042).
19. Do TBVI and WEVI engage in exploitative
competition?
Yes, but it is asymmetrical.
1) Diet diverged between individuals from sympatry
compared to allopatry. WEVI consumed the
higher trophic levels (ie. spiders) in sympatry.
2) Abundance of food declined from fall to winter,
especially in sympatry. Indicates there should be
stronger competition in winter than fall. The
presence of two vireo species in sympatry may
have resulted in decreased food availability.
20. Direct physical interactions are costly in terms of
time away from feeding and energy expended;
receving those interactions are costly for the
same reasons.
Indirect interactions are costly when the more
energetically favorable food is consumed by
another species, leaving less desirable or less
profitable food.
Therefore, both types of competition, whether
interactions are adaptive or not, may result in
costs. But how do you measure ‘cost’?
21. What is corticosterone?
-hormone released in the blood in response to a
stressful event
-stress includes predation attempt, severe
environmental weather, lack of food, etc
-causes behavioral and physiological changes,
including increasing activity (more likely to find food)
and activating gluconeogenesis (releasing
carbohydrates from muscle for energy)
-if present at elevated levels for long periods, can cause
individuals to lose body mass
-the abundance of this hormone is a common way to
assess whether an individual is ‘stressed’ and thus
experiences a ‘cost’ by losing energetic reserves
22. Question:
Do TBVI and WEVI experience physiological
costs from coexistence?
Hypotheses and predictions:
1) If coexistence is stressful, both species will have
higher corticosterone and lower body mass in
sympatry compared to allopatry.
2) If resource decline is stressful, both species will
have higher corticosterone and lower body
mass in the winter than the fall.
23. Methods:
I bled each bird at capture (=baseline corticosterone) and after
30 minutes (=acute corticosterone).
-30 minutes of handling is considered a stressful event, and
elicits an increase in this hormone
I spun the blood in a centrifuge, separated the plasma from the
red blood cells, then froze the plasma at -80°C until
analyzed using an enzyme immunoassay kit.
Results: (ANOVAs; TBVI: n=42; WEVI: n=34)
Baseline corticosterone levels were higher in sympatry than
allopatry (TBVI: p=0.024; WEVI: p=0.05).
-this indicates that the presence of the heterospecific
increased stress
-higher corticosterone can cause increased foraging effort
and the release of stored energy reserves
24. TBVI body mass was
negatively related to
acute corticosterone
(p=0.0008).
0
2
4
6
8
10
12
14
16
18
0 10 20 30 40 50 60 70 80
Bodymass(g)
Acute plasma corticosterone concentration (ng/mL)
-the more corticosterone in your
system, the more you use skeletal
muscle as an energy source,
resulting in lower body mass
Body mass also declined from the fall to the winter
in TBVI (p<0.0001), but not in WEVI. Neither
species showed a difference in body mass in
sympatry compared to allopatry.
25. TBVI are dominant and really aggressive towards
the subordinate WEVI, yet their territories
overlap.
WEVI eat different food when they coexist with
TBVI, especially when resources decline.
TBVI and WEVI are more stressed when they
coexist, and TBVI are stressed as resources
decline.
Both species experience negative effects of
coexistence. This is the first time this has been
demonstrated during the non-breeding season.
26. Why do we care?
-as the climate changes and habitat is lost, ecologically
similar species will be forced to share smaller fragments
of habitat, potentially leading to an increase in the
occurrence and intensity of interspecific interactions.
-previous studies have shown that territory location,
quality of diet, and physiological condition can all affect
survival, and thus fitness and population processes.
-effects on individuals during the non-breeding season
have been shown to carry-over to the breeding season in
both migrants and residents, affecting both survival and
reproduction, and thus fitness.
-microevolutionary processes: subpopulations under strong
selection to adapt to conditions on the wintering ground
(i.e. presence of heterospecifics) may experience a
mismatch to conditions during their breeding season.
27. Funding:
UC Mexus small grant
Gerace Research Center grant
AOU research grant
Ralph Schreiber reseach grant
UCLA Dept of EEB research grants
NSERC PGS fellowship
Committee:
Greg Grether
Catherine Sugar
Tom Smith
Peter Narins
Field/lab work:
E. Rutherford, E. Quiros,
M. Akresh, E. Curd, M. Rensel
Logistic support:
Gerace Research Center
Friends of the Environment
Los Tuxtlas Research Station
BEST Commission, the Bahamas
C. Macias Garcia, UNAM