Bio 250 Exam 3 Questions And All
Correct Answers.
Gause's principle of competitive exclusion - Answer - no two species can occupy identical niches
indefinitely when resources are limiting
-either they can't exist for a long time or there niches are somewhat different
sympatric - Answer species often avoid competition by living in different portions of the habitat, or
using different food or other resources
ex: anolis lizards on caribbean island
character displacement - Answer differences between symmetric species that are favored by natural
selection in order to partition resources and reduce competition
ex: Darwin's finches
reproductive character displacement - Answer species recognition and mate choice using wing
pigmentation in damselflies
predation - Answer one organism consuming another, kills prey pretty much immediately
sea otters - Answer -predators to sea urchin
-almost total removal of sea otters from CA during 1800s
-led to increase in red urchins
-and decrease of kelp beds
predation and coevolution - Answer -predation is strong selection pressure on prey populations, so the
prey may evolve traits to avoid capture
-natural selection favors traits in the predators to overcome the prey adaptations
-coevolution & arms race
-can also happen with herbivores and plants, parasites and hosts
, chemical defenses - Answer -secondary chemical compounds that are toxic or disrupt development
-ex: mustard oil in Brassicaceae and cabbage white butterflies
mechanical barriers to herbivory - Answer trichomes, glandular exudates, latex and egg mimics
passionflower plants and heliconius butterflies - Answer -lay their eggs on passion vines and
caterpillars eat the leaves
-the butterflies search visually for the plants, so intense selection pressure on appearance
egg mimics - Answer _______ ___________ reduce the amount of oviposition because adults avoid
larval competition (cannibalism and egg predation)
-bigger heads
-modified tarsus
-longer proboscis (aphids) - Answer adaptations to mechanical defenses
secondary compounds - Answer animals can use _______________ ______________ of plants for their
own protections
monarch butterflies and milkweed - Answer -monarch butterfly caterpillars can feed on toxic milk weed
and store up cardiac glycosides in fat to protect themselves from predators
eating plant toxins - Answer -cinnabar moth and african variegated grasshopper
-get toxins called pyrrolizidone alkaloids (from ragwort)
-both species evolved enzyme that allows them to store the toxin for self defense
chemical defenses of animals - Answer poison dart frogs produce toxic alkaloids in mucus, distasteful
and deadly to animals to try and eat
Correct Answers.
Gause's principle of competitive exclusion - Answer - no two species can occupy identical niches
indefinitely when resources are limiting
-either they can't exist for a long time or there niches are somewhat different
sympatric - Answer species often avoid competition by living in different portions of the habitat, or
using different food or other resources
ex: anolis lizards on caribbean island
character displacement - Answer differences between symmetric species that are favored by natural
selection in order to partition resources and reduce competition
ex: Darwin's finches
reproductive character displacement - Answer species recognition and mate choice using wing
pigmentation in damselflies
predation - Answer one organism consuming another, kills prey pretty much immediately
sea otters - Answer -predators to sea urchin
-almost total removal of sea otters from CA during 1800s
-led to increase in red urchins
-and decrease of kelp beds
predation and coevolution - Answer -predation is strong selection pressure on prey populations, so the
prey may evolve traits to avoid capture
-natural selection favors traits in the predators to overcome the prey adaptations
-coevolution & arms race
-can also happen with herbivores and plants, parasites and hosts
, chemical defenses - Answer -secondary chemical compounds that are toxic or disrupt development
-ex: mustard oil in Brassicaceae and cabbage white butterflies
mechanical barriers to herbivory - Answer trichomes, glandular exudates, latex and egg mimics
passionflower plants and heliconius butterflies - Answer -lay their eggs on passion vines and
caterpillars eat the leaves
-the butterflies search visually for the plants, so intense selection pressure on appearance
egg mimics - Answer _______ ___________ reduce the amount of oviposition because adults avoid
larval competition (cannibalism and egg predation)
-bigger heads
-modified tarsus
-longer proboscis (aphids) - Answer adaptations to mechanical defenses
secondary compounds - Answer animals can use _______________ ______________ of plants for their
own protections
monarch butterflies and milkweed - Answer -monarch butterfly caterpillars can feed on toxic milk weed
and store up cardiac glycosides in fat to protect themselves from predators
eating plant toxins - Answer -cinnabar moth and african variegated grasshopper
-get toxins called pyrrolizidone alkaloids (from ragwort)
-both species evolved enzyme that allows them to store the toxin for self defense
chemical defenses of animals - Answer poison dart frogs produce toxic alkaloids in mucus, distasteful
and deadly to animals to try and eat
