Chapter 14: What are Species? Flashcards
define speciation
process by which one species splits into two or more species
What accounts for both the unity and diversity of life?
speciation
describe the biological species concept
a species is a group of populations whose members can interbreed (produce fertile offspring) with each other but not with members of other species
which concept emphasizes reproductive isolation?
biological species concept
describe the morphological species concept
based on observable physical traits and can be applied to asexual organisms and fossils
describe the ecological species concept
defines a species by its ecological niche and focuses on unique adaptations to a biological community
describe the phylogenetic species concept
defines a species as the smallest group of individuals that share a common ancestor forming one branch of the tree of life
What keeps species separate?
reproductive barriers
purpose of reproductive barriers…
- serve to isolate gene pools of species
2. prevent interbreeding
How are reproductive barriers categorized?
as prezygotic and postzygotic
examples of prezygotic barriers include…
- habitat isolation
- temporal isolation
- behavioral isolation
- mechanical isolation
- gametic isolation
habitat isolation is the…
lack of opportunities to encounter each other
behavioral isolation refers to…
different courtship rituals
mechanical isolation refers to…
physical incompatibility of reproductive parts
gametic isolation refers to…
the molecular incompatibility of eggs and sperm or pollen and stigma
examples of postzygotic barriers
- reduced hybrid viability
- reduced hybrid fertility
- hybrid breakdown
reduced hybrid viability refers to
the hybrid development/ survival impaired by interaction of parental gametes
reduced hybrid fertility refers to..
the vigorous hybrids that cannot produce viable offspring
hybrid breakdown refers to…
viable and fertile hybrids with feeble or sterile offspring
define allopatric speciation
the interruption of gene flow between populations caused by physical/ geographical isolation
How do reproductive barriers arise?
environment of isolated population may include different foods, pollinators, predators
define sympatric speciation
a new species arises within the same geographical area as the parent species
What can lead to sympatric and allopatric speciation?
habitat differentiation and sexual selection
define polyploidy
duplication of the chromosome number due to errors in cell division
many plant species have evolved through
polyploidy
How does the development of polyploidy species happen?
- within a single species
- through hybirdization
what leads to speciation?
sexual selection
biologist can test hypothesis about the process of speciation by
studying species that arose recently
what has been an important part of the diversification of cichlids in Lake Victoria?
sexual selection
define adaptive radiation
evolution of diverse species from a common ancestor
what has lead to adaptive radiations of species?
-repeated isolation
-recolonization
speciation
define hybrid zones
regions in which population of different species overlap and produce a hybrid offspring
what happens when separated population of closely related species come back into contact with one another?
hybrid zone occurs
3 types of hybrid zones
- reinforcement
- fusion (collapse)
- stability
describe reinforcement
–
describe fusion
bright colored stripped fish + black/white stripped fish = dull colored stripped fish
describe stability
–
what are the 2 models for the rate of speciation?
- punctuated equilibria
2. gradualism
define punctuated equilibria
evolutionary pattern where species change the most from ancestors and then very little for the rest of their lives
define gradualism
evolutionary pattern where species evolve in a dispersed manner throughout generations (slight changes)
