Chapter 22-23 test Flashcards
What is speciation?
The process by which one species splits into multiple species, leading to diversity and linking features of animals
What is microevolution and macroevolution?
Microevolution: Changes over time in allele frequencies in a population
Macroevolution: The broad pattern of evolution above the species level
What is the biological species concept?
A concept that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring with members of other such groups
What plays a key role in the formation of new species and keeping them apart?
Gene flow
What is reproductive isolation?
biological barriers that impede members of two species from interbreeding and producing viable, fertile offspring
In what ways do prezygotic barriers act?
- impeding member of different species from attempting to mate
- preventing an attempted mating from being completed successfully
- if by hindering fertilization from successful mating from fertilization
What is temporal isolation?
Species that breed during different times of the day, seasons or years can not mix gametes
What is mechanical isolation?
Mating is attempted but morphological differences prevent successful completion
What is gametic isolation?
Sperm of one species can not fertilize the eggs of another species. Sperm may not be able to survive in the reproductive tract of females or biochemical mechanisms may prevent sperm penetration
What are the types of postzygotic barriers?
- Reduced hybrid viability: Hybrid is jot fit to survive environment
- Reduced hybrid fertility: Hybrids are infertile because of gene/chromosome count differences in parents
- Hybrid breakdown: Some hybrids are fertile and viable, but their offspring are not
What are strengths and weaknesses to the biological species concept?
Strength: directs or attention to a way speciation occurs
Weaknesses: There is no way to evaluate reproductive isolation of fossils, it does not apply to asexual organisms and there are organisms that are isolated but experience gene flow
What is the morphological species concept? What is a weakness of this concept?
A concept that characterizes species by body shape and other structural features. It is subjective and can create disagreement
What is the ecological species concept? How is it different from the biological species concept?
A concept that views a species in terms of its ecological niche, the sum of how members of the species interact with living and nonliving parts of their environment. Unlike the biological species concept, this can accomodate asexual and sexual species and emphasizes the role of disruptive natural selection
What is the phylogenetic species concept? What is the weakness of this concept?
A concept that defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life. This concept can cause sufficiently different species to be classified together and determining the degree of difference necessary is difficult as well
What are 2 ways speciation occurs?
Allopatric: Gene flow is interrupted when a population is divided into geographically isolated populations
Sympatric: speciation occurs in populations that live in the same geographic area
What is the difference between biological barriers and physical separation?
Even though both inhibit reproduction, biological reproduction is intrinsic to the organism itself
what is polyploidy?
An accident in cell division resulting in extra sets of chromosomes
What is an autopolyploid?
an individual that has more than two chromosome sets that are all derived from 2 species
What is an allopolyploid?
A fertile polyploid that can mate with other allopolyploids, they represent a new species
In what organisms is polyploidy common?
Plants, not so much so in animals
What role does habitat differentiation play in sympatric speciation?
When genetic factors enable a subpopulation to exploit a habitat or resource not used by the parent population
What pattern does a hybrid zone typically follow?
Hybrid zones are present where the habitats of interbreeding species meet, often in groups of isolated patches across a landscape
What are the possibilities of a hybrid zone if speciation isnt occurring?
- Reinforcement: Hybrids are less fit than parent species and natural selection strengthens prezygotic barriers. Barriers are reinforce and barriers between species are strong in sympatric than allopatric populations
- Fusion: Barriers to reproduction become weaker and the gene pools of the two species become increasingly alike, reverse speciation
- Stability: Hybrids can continue to be reproduced because they are viable. These are observed where the hybrids are naturally selected AGAINST, because these zones are small and parent species from both populations migrate to this zone
What are punctuated equilibria? Why does this occur?
Periods of apparent stability punctuated change in the fossil record. This occurs because changes over shorter periods of time are distinguished in the fossil record
What does the fossil record say about speciation rates?
Fossils that display a punctuated pattern suggest that once the process of speciation, it can be completed relatively rapidly
What type of evolution do fossils reveal?
macroevolution
What are sedimentary rock layers called?
strata
What is the fossil record biased towards?
In favor of species that existed for a long time, were abundant and widespread in certain kinds of environments, and had hard shells/skeletons/fossilized parts
what is radiometric dating?
One common technique of determining absolute age based on the decay of radioactive isotopes
What are stromalites?
Layered rocks that form when certain prokaryotes bind thin films of sediment together
What group of organisms did mammals come from?
cynodonts
What is the theory of plate tectonics?
A theory that the continents are apart of great plates of earth’s crust that essentially float on the hot, underlying portion of the mantle
What process does continental drift promote?
Allopatric speciation
What mass extinctions receive the most attention?
Permian(Separating palaeozoic and mesozoic eras) and cretaceous(separating mesozoic and cenozoic eras)
What occurred in the permian mass extinction?
Permian: Occurred at a time of enormous volcanic activity in Siberia. Huge amounts of lava covered the earth and enough carbon dioxide was produced to warm the earth and slow the mixing of oceans due to a lower temp difference between poles and equator. This harmed O2 breathing organisms and encouraged growth of anaerobic bacteria that emit poisonous H2S
What happened in the cretaceous mass extinction?
A thin layer of clay rich Iridium on the fossil record indicates the falling of extraterrestrial objects to earth.The Iridium at the time formed a cloud that would have blocked sunlight and severely disturbed the global climate for several months
What are adaptive radiations?
Periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities
Which area is the best example of regional adaptive radiation?
Hawaiian islands
What is herterochrony?
An evolutionary change in the rate or timing of developmental events
What is paedomorphosis?
A condition where heterochrony alters the timing of reproductive development relative to nonreproductive development, causing organisms to be sexually mature at a different stage than their ancestors
What is the function of homeotic genes?
To determine basic spatial features such as wing or leg placement on an organism
What are Hox genes?
A class of homeotic genes that provide positional information in an animal embryo
What is the cambrian explosion?
The sudden and rapid diversification of animal phyla 535-525 mya
What is responsible for change in form of organisms?
Change in the regulation of developmental genes
What do the Ubx and Pitx1 genes regulate?
Ubx: body form in insects and crustaceans
Pitx1: Spines in stickleback fish
What are exaptations?
Structures that evolved in one context but co-opt for another
What is evolution the result of?
Interactions between organisms and their current environments
