unit 4 chapter 24 quiz

a mechanisms of sympatric speciation?

-Polyploidy -Habitat differentiation -Sexual selection

Phylogenetic species concept

-defines a species as the smallest group of individuals on a phylogenetic tree -applies to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species

Morphological species concept

-defines a species by structural features -applies to sexual and asexual species but relies on subjective criteria

BSC is limitations

-it can't resolve organisms that are asexual or extinct -emphasizes absence of gene flow, however gene flow can occur between distinct species (grolar-bears)

Ecological species concept

-views a species in terms of its ecological niche -applies to sexual and asexual species and emphasizes the role of disruptive selection

Tigers once ranged all throughout eastern Asia (see map above). Their range has been greatly reduced and fragmented, so now there are several subspecies of tigers; Bengal tigers, Siberian tigers, Sumatran tigers and a few more. At present, they are still recognized as subspecies of Panthera tigris because they can still interbreed in captivity and produce fertile offspring, but in the distant future they may become reproductively isolated by _____ speciation.

Allopatric

Lions and tigers can mate in captivity to produce viable offspring (ligers and tions, depending on which species is the mother and which is the father). Ligers do not occur in nature though, since lions and tigers do not have overlapping ranges in nature. This is an example of the prezygotic species barrier, ________.

Habitat isolation

Another reason we consider lions and tigers to be discrete species is that they are easily distinguishable. If I told you the image above was a lion, you would not believe me, because you know what a lion looks like, and what a tiger looks like. We are applying the:

Morphological species concept

In addition, while liger females are fertile, liger males are sterile. This is a case of:

Reduced hybrid fertility

The biological species concept would best be applied to:

bengal tigers

PRE-ZYGOTIC BARRIERS

block fertilization from occurring by: -Impeding different species from attempting to mate -Preventing the successful completion of mating -Hindering fertilization if mating is successful

sexual selection

can drive sympatric speciation

Microevolution

consists of changes on allele frequency in a population over time

the key to species membership is

gene flow (gene flow holds the phenotype of a population together)

fusion

hybrids are equally fit to parent species and reproductive break down throughout the range of all species

reinforcement

hybrids are less fit than the parent species; reproductive barriers lead to hybrids across generations

reproductive isolation

is the existence of biological factors (barriers) that impede 2 species from producing viable, fertile offspring

stability

parent species mate, and hybrids are fit within the hybrid zone only

POST-ZYGOTIC BARRIERS

prevent the hybrid zygote from developing into a viable, fertile adult

macroevolution

refers to broad patterns of evolutionary change above the species level

Habitat differentiation

sympatric speciation can also result from the appearance of new ecological niches

hybrids

the offspring of crosses between different species