Chapter 14 The origin species Flashcards
What creates opportunities for speciation, but it does not necessarily lead to new species
The answer is geographic isolation
This only occurs when the gene pools undergoes changes in establishing reproductive barriers.
Speciation
A new species arises within the same geographic area as its parent species
Sympatric speciation
What are the factors that can reduce gene flow in sympatric populations?
1) polypoidy
2)habitat diffirentiation
3)sexual selection
Polypoid
cells have more than two complete sets of chromosomes
True or false. Odd numbers of chromosomes can form homologous pairs during meiosis?
False. It cannot odd numbers of chromosomes cannot form homologous pairs during meiosis
in short, odd numbers=sterile
occurs when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another.
sympatric speciation
Both habitat differentiation and sexual selection can also contribute to the formation of _______ between _____ populations
sexual reproductive barriers between the allopatric populations
Focused on the role of natural selection in the gradual adaptation of a population to its environment
microevolution
the process by which one species splits into two or more species
speciation
what happens each time speciation occurs?
the diversity of life increases
Biological species concept
defines a species as a group populations whose members have the potential to interbreed in nature and produce fertile offspring (offspring themselves can reproduce)
the existense of barriers that stop members of two species from producing viable, fertile, offpsring with each other
reproductive isolation
many pairs of species are distinct and et are capable of interbreeding. the offspring of pairs of clearly distinct species are called
hybrids
for most organism- sexual,asexuall, and fossils alike classification is based mainly on…..
physical traits such as shape,size,and other features of morphology (form)
frequently applied in such cases, as it relies entirely on the physical structures or traits of an organism.
the morphological species concept
what are the advantage and disadvantage of morphological species concept?
advantage: it can be applied to asexual organism and fossils and does not require information on possible interbreeding.
disadvantage: this approach relies on subjective criteria, researchers may disagree on which features distinguish a species.
focusing on unique adaptation to particular roles in a biological community example: two fish may be similar in appearance but distinguishable based on what they eat or depths of water in which they are usually found.
ecological species concept
defines a species as the smallest group of individuals that share a common ancestor and from one branch on the tree of life
phylogenetic species concept
which species concepts could you apply to both sexual and asexual species?
the morphological, ecological, and phylogenetic species concepts could all be sued because they do not rely on the criterion of reproductive isolation
what prevents species that are closely related from interbreeding?
reproductive isolation
the various type of reproductive barriers that isolate the gene pool of species can be categorized as either ….
1) prezygotic barriers
2)postzygotic barriers
prevent making or fertilization between species
prezygotic barriers
operate after hybrid zygotes have formed
postzygotic barriers
