1) The document discusses the differences between choice mate and predation. It provides examples of sexual selection through mate choice in animals and how brightly colored males are chosen by females.
2) It then describes two experiments that test the influences of mate choice and predation on animals. One study found that a spider acquires odors from the mosquitoes it eats that makes it more attractive to mates. The other found that female swordtail fish change their mate preferences after exposure to predator videos.
3) The document seeks to explain mate choice and sexual selection in animals using examples from field and laboratory experiments that show how both mate choice and predation influence evolution.
Social organization and social behaviour in insectsPoojaVishnoi7
Introduction
Properties of a society
Advantages of a society
Disadvantages of a society
Social organisation and social behaviour in insects:-
1. Termites
2.Honeybees
3.Ants
4.Yellow wasp
Animals secrete pheromones to trigger many types of behaviors, including:
raising an alarm
signaling a food trail
triggering sexual arousal
tell other female insects to lay their eggs elsewhere
delineating a territory
bond between mother and offspring
warning another animal to back off
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
Ethology is the scientific and objective study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Ethology is a branch of zoology concerned with the study of animal behavior. Ethologists take a comparative approach, studying behaviors ranging from kinship, cooperation, and parental investment, to conflict, sexual selection, and aggression across a variety of species.
Reproductive behaviour: 1-Sexual behaviour in animalsrhfayed
Reproductive Behaviour involve behaviour patterns associated with courtship, copulation, birth, maternal care and with suckling attempts of newborn. It is species specific behaviour
this presentation includes morphological and biochemical changes that takes place during amphibian metamorphosis. it also includes hormonal control and coordination during metamorphosis.
scott gilbert 6th edition is a very good book for this topic.
also available on net on ncbi site
happy studying :)
types of orientation- primary and secondary, different types of kinesis - orthokinesis and klinokinesis and taxis - tropotaxis, klinotaxis, menotaxis, transverse orientation, dosal light reaction and ventral light reaction
Parental care in amphibians and reptilesayesha sahi
Any form of parental behavior that appears likely to increase the fitness of the parent’s offspring.
Parents of some animals go to great lengths to increase their offspring’s survival prospects by protecting them from predators, food shortages, desiccation, and a range of other environmental hazards.
First off all they decide the oviposition site.
Any place where small puddles of still water form can provide a suitable nesting site. Sites range from potholes, tapir tracks, and large leaves to human made ditches, road ruts, and even plastic bowls
Rheobatrachus females brooded tadpoles in their stomachs, and the young emerged from the females
In case of moor frogs, males stay to guard the clutch. They attack anyone who
approaches it! They do not leave the post until tadpoles hatch. Only then, starving fathers
go to land and may eat well.
Habitat is a fundamental niche which refers to the multidimensional space with proximate factors. Habitat provides shelter, food, protection, mates, space for breeding, feeding, resting, roosting, courtship, grooming, sleeping etc.
Social organization and social behaviour in insectsPoojaVishnoi7
Introduction
Properties of a society
Advantages of a society
Disadvantages of a society
Social organisation and social behaviour in insects:-
1. Termites
2.Honeybees
3.Ants
4.Yellow wasp
Animals secrete pheromones to trigger many types of behaviors, including:
raising an alarm
signaling a food trail
triggering sexual arousal
tell other female insects to lay their eggs elsewhere
delineating a territory
bond between mother and offspring
warning another animal to back off
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
Ethology is the scientific and objective study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Ethology is a branch of zoology concerned with the study of animal behavior. Ethologists take a comparative approach, studying behaviors ranging from kinship, cooperation, and parental investment, to conflict, sexual selection, and aggression across a variety of species.
Reproductive behaviour: 1-Sexual behaviour in animalsrhfayed
Reproductive Behaviour involve behaviour patterns associated with courtship, copulation, birth, maternal care and with suckling attempts of newborn. It is species specific behaviour
this presentation includes morphological and biochemical changes that takes place during amphibian metamorphosis. it also includes hormonal control and coordination during metamorphosis.
scott gilbert 6th edition is a very good book for this topic.
also available on net on ncbi site
happy studying :)
types of orientation- primary and secondary, different types of kinesis - orthokinesis and klinokinesis and taxis - tropotaxis, klinotaxis, menotaxis, transverse orientation, dosal light reaction and ventral light reaction
Parental care in amphibians and reptilesayesha sahi
Any form of parental behavior that appears likely to increase the fitness of the parent’s offspring.
Parents of some animals go to great lengths to increase their offspring’s survival prospects by protecting them from predators, food shortages, desiccation, and a range of other environmental hazards.
First off all they decide the oviposition site.
Any place where small puddles of still water form can provide a suitable nesting site. Sites range from potholes, tapir tracks, and large leaves to human made ditches, road ruts, and even plastic bowls
Rheobatrachus females brooded tadpoles in their stomachs, and the young emerged from the females
In case of moor frogs, males stay to guard the clutch. They attack anyone who
approaches it! They do not leave the post until tadpoles hatch. Only then, starving fathers
go to land and may eat well.
Habitat is a fundamental niche which refers to the multidimensional space with proximate factors. Habitat provides shelter, food, protection, mates, space for breeding, feeding, resting, roosting, courtship, grooming, sleeping etc.
When males only contribution to offspring is their sperm, females .pdfanurag1231
When males\' only contribution to offspring is their sperm, females are particularly choosy. With
this high level of female choice, sexual ornaments are seen in males, where the ornaments reflect
the male\'s social status. Two hypotheses have been proposed to conceptualize the genetic
benefits from female mate choice.
First, the good genes hypothesis suggests that female choice is for higher genetic quality and that
this preference is favored because it increases fitness of the offspring. This includes Zahavi\'s
handicap hypothesis and Hamilton and Zuk\'s host and parasite arms race. Zahavi\'s handicap
hypothesis was proposed within the context of looking at elaborate male sexual displays. He
suggested that females favor ornamented traits because they are handicaps and are indicators of
the male\'s genetic quality. Since these ornamented traits are hazards, the male\'s survival must
be indicative of his high genetic quality in other areas. In this way, the degree that a male
expresses his sexual display indicates to the female his genetic quality. Zuk and Hamilton
proposed a hypothesis after observing disease as a powerful selective pressure on a rabbit
population. They suggested that sexual displays were indicators of resistance of disease on a
genetic level.
Such \'choosiness\' from the female individuals can be seen in wasp species too, especially
among Polistes dominula wasps. The females tend to prefer males with smaller, more elliptically
shaped spots than those with larger and more irregularly shaped spots. Those males would have
reproductive superiority over males with irregular spots.
Fisher\'s hypothesis of runaway sexual selection suggests that female preference is genetically
correlated with male traits and that the preference co-evolves with the evolution of that trait, thus
the preference is under indirect selection. Fisher suggests that female preference began because
the trait indicated the male’s quality. The female preference spread, so that the females’ offspring
now benefited from the higher quality from specific trait but also greater attractiveness to mates.
Eventually, the trait will only represent attractiveness to mates and no longer represent increased
survival.
An example of mate choice by genes is seen in the cichlid fish Tropheus moorii where males
provide no parental care. An experiment found that a female T. moorii is more likely to choose a
mate with the same color morph as her own. In another experiment, females have been shown to
share preferences for the same males when given two to choose from, meaning some males get
to reproduce more often than others
Solution
When males\' only contribution to offspring is their sperm, females are particularly choosy. With
this high level of female choice, sexual ornaments are seen in males, where the ornaments reflect
the male\'s social status. Two hypotheses have been proposed to conceptualize the genetic
benefits from female mate choice.
First, the good genes hypothesis.
in natural selection, explain what is a sexual selection, neutral va.pdfjaronkyleigh59760
in natural selection, explain what is a sexual selection, neutral variation and balancing selection
Solution
The concept of natural selection explains that how a species can have breeding populations
adapted to local conditions. Based on the principle of natural selection the selection of genotypes
occurs and that would result in offspring with better reproductive capabilities. Natural selection
always results in better survival of an organism, so the genetic changes driven by the natural
selection make the species to adapt to the local conditions so that they can survive. These species
may exhibit high genetic variation may be because out breeding, but gradually due to the
inbreeding in these adapted species, the genetic variation will be minimized and they evolve as a
separate species.
The sexual selection refers that a species which exhibit dominant sexual characters to the
opposite partner has the ability to mate with female and expand its gene pool.
Natural variation: In variation selection, the traits within the organisms undergo mutations to
allow the organism to best adapt to the environment by means of natural selection (Darwinian
evolution), these mutations are inherited by the nest generation offspring. In case of
transformational selection or Lamarck’s theory, the individual organisms change by inheriting
the transformations within a generation.
The three types of selection that we observe in speciation are disruptive selection, stabilizing
selection and directional selection. Disruptive selection occurs due to the selection for the
extreme values of traits instead of intermediate values. This divides the population into two
different groups. Disruptive selection is one of the main driving forces of sympatric speciation,
which occurs when there are no physical barriers that prevent species to mate together. The
occurrence of speciation may be depending on the availability of different food sources and
existence of different shelters. When comes to the balanced selection the allele frequencies
remain contestant throughout the evolution..
Modeling Sexual Selection with Agent-Based ModelsEsteban Ribero
The paper discusses a well-known principle in evolutionary biology called the handicap principle. Two agent-based-models were developed to illustrate the principle in an attempt to better understand its implications for the study of human behavior.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
2. Choice Mate versus Predation
• Describe sexual selection
• Contrast intrasexual selection and intersexual selection
• Give examples of field or laboratory experiment designed
to test the influences of mate choice and predation in
animals
Intended Learning Outcomes (ILOs)
3. Pre-Interactive Activity :
1. What type of selection is most likely responsible
for the large antlers seen on male elk?
A. Intersexual selection
B. Intrasexual selection
C. Group selection
D. Kin selection
MATE -MATCH
5. Pre-Interactive Activity :
3. Select the correct statement.
A. Sexual selection is the same as natural selection.
B. Sexual selection is a type of natural selection.
C. Sexual selection is the opposite of natural selection.
6. Pre-Interactive Activity :
4. If males compete against each other for access to
females, and females choose among males for mates,
then we would expect females to be brightly colored
and males to be drab.
A.TRUE
B. FALSE
7. Pre-Interactive Activity :
4. If males compete against each other for access to
females, and females choose among males for mates,
then we would expect females to be brightly colored
and males to be drab.
A.TRUE
B. FALSE
9. CORRECT ANSWER
ANSWER PERCENTAGE MATE-MATCH
1. B 5 = 100 % American
2. B 4 = 95 % European
3. B 3 = 90 % Asian
4. B 2 = 85 % African
5. B 1 = 80 % Indian
0 = 75 % Afghan
Absent = 70 % Mongolian
10. What is Choice Mate ?
• Differences in reproductive value
• Behavior patterns exhibited by one sex that
makes the member of this sex more likely to
mate with specific members of the opposite sex
• Limitations to reproduce by gametes
11. What is Predation ?
Predation is a type of
ecological interaction where
one of the species kills and
feeds on the other.
The organism that kills and
feeds on the dead organism
is called the predator,
whereas the organism that
gets killed is called the prey.
12. SEXUAL SELECTION
• a special type of natural
selection in which the sexes
acquire distinct forms either
because the members of one
sex choose mates with
particular features or because
in the competition for mates
among the members of one
sex only those with certain
traits succeed.
13. SEXUAL SELECTION
Sexual selection creates
colorful differences
between sexes (sexual
dimorphism) in Goldie's
bird-of-paradise. Male
above; female below.
Painting by John Gerrard
Keulemans (d.1912)
14. What is Natural Selection ?
-the process whereby organisms
better adapted to their
environment tend to survive and
produce more offspring. The
theory of its action was first fully
expounded by Charles Darwin and
is now believed to be the main
process that brings about
evolution.Compare with survival of
the fittest.
15.
16. Which is a special case of natural selection?
Sexual selection is a
"special case" of
natural selection.
Sexual selection acts
on an organism's
ability to obtain (often
by any means
necessary!) or
successfully copulate
with a mate.
17. Which is a special case of natural selection?
Rooster (Left )has brightly colored to attract mates, while chicken (middle) has
dully colored to protect the eggs and young effectively. The same is true of
mallard ducks (right).
18.
19. Involves characteristics which affect the outcome of
competition among members of one sex for access to
members of the other sex
1. Intrasexual Selection
20.
21.
22. Males and females often look different. Sexual Dimorphism. Males
and females differ in appearance (secondary sexual characteristics)
Primary sexual characteristics : reproductive organs
23.
24.
25.
26. 2. Intersexual Selection
-would influence the evolution of secondary sexual
characteristics which determine the relative “
attractiveness” of members of one sex to the other sex
27.
28.
29.
30.
31.
32.
33.
34. So ,why are male birds often
More brightly colored than females ?
Choice
Females just choose more brightly
colored males.
35. So ,why are male birds often
More brightly colored than females
Choice
Females just choose more brightly
colored males( so do predators !
36. Monogamy -
• defined as a pair bond between two
adult animals of the same species –
typically of the opposite sex.
• the habit of one mate at a time.
• This pair may cohabitate in an area or
territory for some duration of time,
and in some cases may copulate and
reproduce with only each other.
Mating System :
37. So ,why are male birds often
More brightly colored than females
Choice
Females just choose more brightly
colored males( so do predators !
38. So ,why are male birds often
More brightly colored than females
Choice
Females just choose more brightly
colored males( so do predators !
39. So ,why are male birds often
More brightly colored than females
Choice
Females just choose more brightly
colored males( so do predators !
40. So ,why are male birds often
More brightly colored than females
Choice
Females just choose more brightly
colored males( so do predators !
41. So ,why are male birds often
How blood-derived odor influences mate-choice
decisions by a mosquito-eating predator
By : Fiona R. Crossa, Robert R. Jacksona,b, and
Simon D. Pollardc
https://www.pnas.org/content/pnas/106/46/1941
6.full.pdf
than females
1. Example of field or lab. Experiment designed to test the
influences of mate choice and predation in animals
42. Evarcha culicivora (Araneae, Salticidae)
feeds indirectly on vertebrate blood by
choosing, as preferred prey, blood carrying
female mosquitoes. Mutual mate-choice
behavior is also pronounced in this species. It
was shown that, when E. culicivora feeds
indirectly on blood, it acquires a diet-related
odor that makes it more attractive to the
opposite sex.
How blood-derived odor influences mate-choice
decisions by a mosquito-eating predator
Findings :
43. So ,why are male birds often
The effect of experimental design on the
measurement of mate choice: a meta-analysis
By: Liam R. Dougherty, David M. Shuker
https://academic.oup.com/beheco/article/26/2/3
11/257207
than females
2. Example of field or lab. Experiment designed to test the
influences of mate choice and predation in animals
44. Findings :
Female intraspecific mating preferences are significantly stronger
when tested using a choice paradigm compared with a no-choice
paradigm. We suggest that this is due to the increased cost of
rejection in no-choice tests. This effect may not be limited to mate
choice but may indeed also be applicable to other areas of behavioral
research in which these kinds of choice designs are used, such as
studies of foraging (Kacelnik et al. 2011) or predation (Beatty and
Franks 2012). We also show that the effect of experimental design on
preferences depends on both the type of preference and the sex of
the subject used in a test.
The effect of experimental design on the
measurement of mate choice: a meta-analysis
45. Predator exposure alters female mate choice
in the green swordtail
By : Jerald B. Johnson, Alexandra L. Basolo
https://doi.org/10.1093/beheco/arg046
3. Example of field or lab. Experiment designed to test the
influences of mate choice and predation in animals
46. Female green ,Xiphophorus helleri
;swordtails are capable of flexible mate-
choice behavior in response to changes in
perceived predation risk. After exposure to
the predator video, female interest in the
male with the long sword decreased
significantly, while female interest in the
swordless male increased.
Predator exposure alters female mate choice in the green swordtail
48. In evolution, the selection of a mate based on secondary sex
characteristics. Sexual selection is thought to lead distinct
differences in the appearance of the two sexes within a species. For
example, the tail of the male peacock may be the result of sexual
selection.
Which is an example of sexual selection in evolution?
49. Sexual selection as a consequence of female choice is easy to
understand, provided we are willing to accept that female
preferences exist. If females show a preference, then males with the
preferred trait will leave greater numbers of offspring, and their trait
values will tend to increase in frequency in the population.
How is sexual selection a consequence of female choice?
50. Male fruit flies sometimes transfer a substance to their
mate that inhibits courtship by subsequent males. Male
dunnocks (a small European bird) often peck the cloaca of
their mate until she everts it, sometimes ejecting sperm.
Which is an example of intrasexual selection?
51. Males that impress a female with their plumage, for
instance, are more likely to mate and have offspring. But
Darwin’s fellow scientist Alfred Russel Wallace watched
drab female birds. He credited their more boring colors to
natural selection — adaptations to help a species survive.
Why are male birds more likely to mate?
52. Why do male deer have so many
antlers?
1 Antlers help to dissipate body heat
2 Male deer attracts females with big antlers
3 Antlers are used to fight and earn territory and
breeding rights