Species Flashcards
WHich is the most objective taxon
species
Mammalia
mammals
aves
birds
reptilia
reptiles
amphipia
amphibians
agnatha
jawless fishes
chondrichthyes
cartilaginous fishes
osteichthyes
bony fishes
BIRDS ARE
REPTILES
Reproductive isolation
when groups can no longer exchange genes
a key factor in the divergence of sexually reproducing organisms.
Biological species concept
Groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups
does not refer to organisms that reproduce asexually
morphological species concept
Linnaeus described species based on their appearance
Members of species look alike because they share many alleles.
Townsend’s and Hermit warblers
Hybrids inherit specific-specific mtDNA sequences from their mothers
Most Townsend’s-hermit warbler hybrids have hermit warbler mtDNA
In areas of overlap most Townsend’s warblers maintain their territories and hermit warbler males are most likely to abandon their territories.
Dung beetles
origin of dung beetles occurred in the middle of the Cretaceous, likely in association with dinosaur dung, and with the rise of the angiosperms.
switch in dinosaur diet to incorporate more nutritious and less fibrous angiosperm foliage provided a palatable dung source that ultimately created a new niche for diversification.
At the end of the Cretaceous the loss of dinosaur dung, led to major dung beetle extinctions.
T1R2 gene
Most birds lack an essential subunit (T1R2) of the only known vertebrate sweet receptor.
The ancestral umami receptor (the T1R1-T1R3 heterodimer) was repurposed in hummingbirds to function as a carbohydrate receptor.
Changing taste receptor function enabled hummingbirds to perceive and use nectar, facilitating the massive radiation of hummingbird species.
