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
