The document discusses potential reasons for the observed pattern of higher biodiversity in tropical regions compared to temperate regions, known as the tropical-temperate gradient in species richness. It notes that while larger areas and habitat diversity would predict higher species numbers in Texas compared to Malaysia based on species-area curves, the opposite is true, with far more species found in Malaysia. Various hypotheses for the gradient are examined, such as higher speciation rates in the tropics due to lower extinction risks and higher mutation rates driven by warmer temperatures.
Ppt is made vailable for public for scientifc use.
Population ecology concept and its characteristics explained by using practical examples in a simple language. data is significant for competitive examinations
This slideshow was created for the VCE Environmental Science Online Course, Unit 3: Biodiversity. It explains different methods of assessing biodiversity and discusses several indices for measurement.
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?
Ppt is made vailable for public for scientifc use.
Population ecology concept and its characteristics explained by using practical examples in a simple language. data is significant for competitive examinations
This slideshow was created for the VCE Environmental Science Online Course, Unit 3: Biodiversity. It explains different methods of assessing biodiversity and discusses several indices for measurement.
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?
Environmental Science Table of Contents 37 L.docxYASHU40
Environmental Science Table of Contents
37
Lab 3
Biodiversity
Biodiversity
Concepts to Explore
• Biodiversity
• Species diversity
• Ecosystem diversity
• Genetic diversity
• Natural selection
• Extinction
Introduction
Biodiversity, short for biological diversity, includes the genetic variation between all organisms, species, and
populations, and all of their complex communities and ecosystems. It also reflects to the interrelatedness of
genes, species, and ecosystems and their interactions with the environment. Biodiversity is not evenly distrib-
uted across the globe; rather, it varies greatly and even varies within regions. It is partially ruled by climate,
whereas tropical regions can support more species than a polar climate. In whole, biodiversity represents
variation within three levels:
• Species diversity
• Ecosystem diversity
• Genetic diversity
It should be noted that diversity at one of these levels may
not correspond with diversity within other levels. The degree
of biodiversity, and thus the health of an ecosystem, is im-
pacted when any part of that ecosystem becomes endan-
gered or extinct.
The term species refers to a group of similar organisms that
reproduce among themselves. Species diversity refers to
the variation within and between populations of species, as
well as between different species. Sexual reproduction criti-
cally contributes to the variation within species. For exam-
ple, a pea plant that is cross-fertilized with another pea plant
can produce offspring with four different looks! This genetic
mixing creates the diversity seen today.
Figure 1: There are more than 32,000 species of
fish – more than any other vertebrate!
39
Biodiversity
Ecosystem diversity examines the different habitats, biological communities, and ecological processes in
the biosphere, as well as variation within an individual ecosystem. The differences in rainforests and deserts
represent the variation between ecosystems. The physical characteristics that determine ecosystem diversity
are complex, and include biotic and abiotic factors.
? Did You Know...
A present day example of natural
selection can be seen in the cray-
fish population. The British crayfish
are crustaceans that live in rivers in
England. The American crayfish
was introduced to the same bodies
of water that were already populat-
ed by the British crayfish. The
American crayfish are larger, more
aggressive and carry an infection
that kills British crayfish but to
which they are immune. As a re-
sult, the British crayfish are de-
creasing in number and are ex-
pected to become extinct in Britain
within the next 50 years. Thus, the
American crayfish have a genetic
variation that gives them an ad-
vantage over the British crayfish to
survive and reproduce.
The variation of genes within individual ...
why are the tropics so diverseplease expaint this queation in det.pdfarihantmobilepoint15
why are the tropics so diverse?
please expaint this queation in details.
Solution
Answer:
Added biodiversity in the tropics as compared to the higher latitudes probably stems from the
flux of photons in the tropics, but our earth is a dynamic system and thus its far more
complicated than that.
Mutations can occur randomly, evolutionarily the strongest contributor is error during DNA
replication. This can be argued to be a function of temperature and if so, then temperature plays a
small role in DNA copying.
Another contributor would be that of the flux of photons. Photons have the ability to cause
mutations and there is a noticeable difference in photon flux between the higher latitudes and the
tropics.
The tropics are enormous, spreading across the waistline of the globe. Increasing size provides
ample opportunity for geographic separation for groups within a species. In conjunction with this
is the fact that this broad band girdling the planet has, overall, fairly constant temperature and
humidity.
The tropics also exhibit relatively stable climatic conditions which will result in steady food
supplies for animals as animals could specialize on 1 to 5 food sources and they would be
available more or less year round.
The richness of tropical rainforests in plant life is perhaps due to high levels of solar energy. The
sun lies overhead during the entire year, there is a great deal of light available to support the
plants in the lower strata, more than twice as much as is available to a temperate forest. And
since plants in the tropics don’t suffer from (low) temperature stress, they can devote their
energies to growth and reproduction at even very low light intensities. Light intensities in
tropical forests are also very patchy and heterogeneous. Thus, plants living under the tall canopy
can specialize in exploiting particular light regimes, many of which are not available in
temperate forests. And with plant diversity comes animal diversity, since all of these plants
provide food and shelter for animals.
High mean annual temperature, primary productivity, and evapotranspiration rates are probably
all involved also, but we do not know whether or not the higher energy levels found in
rainforests are causal factors in the generation of biodiversity
The presence of pathogens is a contributing factor but it complex because their related to higher
temperatures but they will cause speciations as organism will need to develop the ability to
defend against them
Storms and high winds are common in tropical areas, and frequently lead to considerable damage
and the formation of fairly large gaps in forests. When the gap in the forest is small (as when one
or a few trees fall), pioneer species will normally enter the gap and flourish, eventually being
replaced by climax tree species.
Tropical regions are large, as well as topographically complex. As mentioned above, the
complexity of the rainforest environment allows for considerable specialization of org.
PowerPoint presentation that highlights chapters 13 and 14 in Campbell's Essential Biology (3rd. edition). It can also be used for Miller & Levine's Biology (2006 Ed.) for chapters 15-18.
3. Biodiversity Challenge! Area Texas - 696,241 km2 Malaysia 328,600 km2 Number of Ecoregions Texas- 13 Malaysia- 12 Therefore, Texas is larger and has more habitat diversity than Malaysia.
4. Lessons From Biogeography Species-area curves show that larger areas often contain more species Species richness is correlated with habitat diversity Thus, predict that there will be more species in Texas than in Malaysia Not surprising- Everything is Bigger in Texas!!!!
5. Biodiversity Challenge Because of its large size and habitat diversity, Texas is one of the most diverse states in the USA. #1 in number of bird species (477) #1 in the number ofreptiles species (149) # 2 in the number of mammals species (159) # 2 in the number of vascular plant (4,509).
6. How About Malaysia? Mammals = 313 species Birds = 746 species Vascular plants = 15,500 species
7. Terrestrial Biodiversity Texas data from The Nature Conservancy of Texas Malaysia data from Wikipedia and www.mongabay.com
8. Much Greater Terrestrial Species Richness in Malaysia Than in Texas! Texas is an unusually species rich region in the US so it is not a problem with Texas. What causes there to be so many more species in Malaysia than in Texas?
9. Temperate-Tropical Gradient It has been well known for over 200 years than there tend to be more species of organisms living in tropical regions than in temperate regions Temperate-tropical gradient in species richness One of the most studied questions in biology But still don’t understand it very well Over 30 different hypotheses have been proposed
16. Mid-Domain Effect If species vary in their latitudinal ranges (i.e., some species are found across a large range of latitudes and others are found across a very small range) then if the location of species on the globe is random then there will still be more species in the tropics.
17. Mid-Domain Effect The mid-domain effect probably doesn’t explain all of the pattern, but we need to examine whether tropics are more diverse than expected by random chance. Other factors can help to explain the “extra diversity”
18. How Should We Try To Study What Factors Cause Greater Species Richness in the Tropics? Go back to the library analogy for biodiversity How we should attempt to understand patterns of diversity depends on whether ecological communities are full or empty.
19. Tropical-Temperate Gradient Full Number species = number of niches Why more niches in tropics? Not Full Number of species = number of species added – number of species lost Need to focus on biological processes that increase the number of species (speciation and immigration) and those that decrease the number of species (extinction)
20. Temperate-Tropical Gradient To understand why there are so many more species in the tropics than in the temperate regions we need to think about Genetics Evolution Ecology Biogeography
32. What Determines Rates of Speciation Probability of forming geographic isolating barriers And maintaining them long enough for speciation Rate of selection Rate of mutation Generation time
33. More Time For Speciation in the Tropics Some people have proposed that the reason that there are more species in the tropics is that the temperate zones have been colonized more recently so there has been less time for the evolution of new species
34. Higher Rates of Speciation in the Tropics Data from plants show that plants in lower elevations have higher mutation rates than plants from higher elevations Suggest higher metabolic rates in warm temperatures causes higher rates of mutation
35. Lower Rates of Extinction in the Tropics Tropics are the largest biome in the world Large area allows for large population sizes Large population sizes correlate with lower rates of extinction If a species does go locally extinct, then it has the possibility of being “rescued” by immigration from another location in the tropics.
36.
37. Higher Rates of Speciation in the Tropics Plants are ectothermic whereas mammals maintain their bodies at a constant level no matter where they live. Thus, mammals may be less affected by this than plants. Compare mammal species from tropics to temperate zone Found faster evolution Cool climates caused less mutation Red Queen Hypothesis
38. Higher Rates of Speciation in the Tropics Some researchers have found no relationship between rates of mutations and latitude in birds Suggest that the differences in rates of evolution and speciation might be due to differences in generation times. Tropical species breed more often than temperate species so they should evolve faster.