Test 2 Flashcards
Which region is this:
From Mexico to the southern tip of South America?
Neotropics
What clade does the South American Native Ungulates (SANU) belong to?
Meridiungulata
Which group includes sloths, glyptodonts, anteaters, and armadillos?
Xenarthrans
Which group is composed of the ‘terror birds’. Giant, flightless, predatory birds?
Phorusrhacidae
Which group includes both Marsupials and Sprassodonts?
Metatherians
What are the 3 extant Orders of marsupials in the Americas?
- the Didelphimorphia
- the Paucituberculata
- the Microbiotheriidae
When did marsupials diverge from the Eutherians?
90 million years ago
Explain a rafting event.
Animals are washed out to sea during floods and storms and “rafts” made of debris are carried by currents to surrounding islands and continents
Volcanic activity that created uplift near Panama about 2.7 MYA, connecting SA to CA, brought about which event?
The Great American Biotic Interchange
Why did the Neotropic species who ventured North fair worse than their Nearctic counterparts?
due to 2 main issues: competition for resources in a new environment and diversification of forms
- the nearctic outcompeted the neotropic organisms and the Neotropic organisms did not diversify in the north
What can be though of as the same geologic event that created GABI also cut off the Central American Seaway?
The Great American Schism
What is migration?
long distance movement of animals usually on an annual or seasonal basis
What is when large numbers of a species move beyond their normal range sometimes because of food scarcity?
irruptions
What is it called when animals don’t take a long term journey but stay local and move downwards to warmer lowlands?
altitudinal migration
what is it called when animals are driven off course by severe weather and show up in LARGE numbers in a new place?
drift migration
what is it called when an animal or small number of animal end up outside their normal ranges?
vagrancy
what is the primary cue for migration in birds?
length of daylight
what do changes in daylight coincide with? what does this lead to?
- hormonal changes
- Zungunruhe (migratory restlessness)
- birds have higher activity levels and higher levels of fat deposition
what is/are a secondary cue for migration in birds?
local temperature
sex, males return to breeding sites earlier than females
where is bird migration primarily a phenomenon?
Northern Hemisphere
what are the dangers of migration?
natural catastrophes/ severe weather
increased predation
novel pathogens
what are some adaptations birds have evolved for their energy intensive migration?
increased effective area for gas exchange
large hearts
high hemoglobin concentration
high capillary density in flight muscles
What is a reason for why whales migrate to warmer waters?
- warmer waters allow whales to shed their skin in an environment where their core body temperature wouldn’t be jeopardized
- need to molt because the skin has harmful bacteria attached to it
What are the 3 components of natural selection?
variation
heritability
difference in reproductive success
what is it when the allele frequency remains the same over generations
- genetic equilibrium
- the null hypothesis for evolution
What are the 5 condition for Hardy - Weinberg Equilibrium?
- complete random mating
- population is large
- no gene flow
- no mutations/ new alleles
- no natural selection
What are some violations to Hardy - Weinberg?
- non-random mating: assortative and disassortative mating
- non-infinite population, therefore genetic drift
- gene flow
- natural selection
- mutation rate
what are the vast majority of mutations that affect mutations?
deleterious
what are polygenetic traits?
traits controlled by multiple genes
what is directional selection?
when the range of phenotypes shift in one direction due to some individuals being more succesful
what is stabilizing selection?
when natural selection works against the two extremes of the population and favors the intermediate phenotype
what is disruptive selection?
when natural selection favors the extremes at the cost of the intermediate traits
what is evolutionary mismatch?
rapid changes in the environment or novel stimuli that make once adaptive traits, maladaptive
What is background extinction?
the normal amount of organisms that go extinct over a given time period
how can you calculate the rate of extinction over a given time period?
E/MSY
E = the number of extinctions
MSY= per millions of species years
(the number of extinctions expected per 10,000 species per 100 years)
what is a conservative estimate of background extinction for all vertebrate animals?
2 E/MSY
2 extinctions per 10,000 species per 100 years
what is mass extinction?
a widespread, relatively rapid decrease in the biodiversity and abundance of organisms
What is the significance of mass extinctions? Provide an example.
- have enormous effects on evolution
- when the dinosaurs became extinct (End-Cretaceous Mass Extinction) mammals were able to inhabit the niches that became void
When did the End-Ordoviciian Mass Extinction occur?
2 pulses:
- 2 MYA - 443.8 MYA
- 8 MYA - 440.8 MYA
how many species did the End-Ordovician Mass Extinction eliminate?
85% of all species that had lived in the Ordovician
- brachiopods, trilobites, conodonts, and bryozoans
when did the End- Cretaceous Mass Extinction occur?
66 MYA
How many animals went extinct during the End-Cretaceous Mass Extinction?
3/4 of life
- all non-avian dinosaurs and pterosaurs went extinct
- no tetrapods over 55 lbs survived except for sea turtles and crocodilians
what is the most credible cause for the End-Cretaceous Mass Extinction?
the impact of a giant asteroid on the Gulf of Mexico side of the Yucatan Peninsula.
what did the asteroid hitting the earth cause in the End-Cretaceous Mass Extinction?
an impact winter- threw enough particulate matter into the air that sunlight was blocked preventing photosynthesis
What are the pieces of evidence that the asteroid caused the End-Cretaceous MAss Extinction?
- an iridium layer was found globally
- the K-Pg boundary was full of tiny spherules of rock, crystallized from molten rock formed by the impact
- evidence of megatsunamis around the Southern US, Caribbean, and Mexican coasts linked to the impact
What are the probable causes for the Holocene-Anthropocene Extinction?
- agriculture: habitat destructuion and climate change to make land for growing crops and animals
- hunting: removed enough methane from the atmosphere it made the climate unstable
What are the extant jawless fish called?
cyclostomes
what are the 2 main groups of the extant cyclostomes?
hagfish
lamprey
how are the gills of the cyclostomes set up?
in the form of pouches. internal the pouches are connected to the pharynx and externally they are open to the water
what is the form of respiration where a jaw is needed to close and seal off the mouth to prevent water from exiting the mouth instead of the gills called?
the ventilation hypothesis of jaw evolution
what is another method of respiration?
ram ventilation
- fish opens its mouth and swims or the current forces water into its mouth and over the gills
what struct formed the architecture from where the jaw began to evolve?
branchial arches
what is considered to the be the first gnathostomes?
placoderms
what type of bone is the placoderm jaw made up of?
dermal bone
what is the difference between dermal bone and endochondral bone?
dermal bone is formed within the dermis and endochondral bone is formed when cartilage is calcified
Why is it significant that placoderms exhibited dermal bone?
previously it was thought endochondral bone was the ancient condition
how were the jaws of qilinyu rostrata reinforced?
by a small external surface of dermal bone
what is bone found in Qilinyu present in the cheek of most living animals?
jugal bone
zygomatic bone- mammals
