bio120 test 2

clade

mrca + all descendants

monophyly

mrca + all descendants

paraphyly

mrca + some descendants

polyphyly

no mrca + some descendants

synapomorphy

a trait that all species in a clade share, which evolved on a branch leading to that clade

homoplasy

similar trait not due to ancestry

2 primary sources of macroevolutionary insights

1) paleontology

2) phylogenetics

biological species concept

species are a group of interbreeding natural populations that are reproductively isolated from others such groups

does reproductive isolation have to be absolute for the BSC

no

allopatric vs sympatric isolation

speciation occurs due to geographic isolation vs. in the same location due to mutations and reproductive preferences

processes where reproductive isolation may occur

finding mate —> fertilization —> development and growth of zygote —> adult survival and reproduction—> growth and survival of offspring

define prezygotic barriers

barriers that prevent successful mating and/or fertilization

types of prezygotic barriers

geographical, ecological, temporal, behavioral, mechanical, cellular

how are apple maggot flies an example of prezygotic barriers

some flies started preferring introduced apples over native hawthorns —> temporal isolation led to divergence

types of intrinsic post zygotic barriers

inviability, sterility, abnormal development of zygote

extrinsic post zygotic barriers occur when

hybrids are less fit in an environment compared to either of its parental lineages

ecological speciation

speciation because of adaptation

adaptive radiation

process of adaptations generating diversity

4 features of adaptive radiation

1) recent common ancestor

2) phenotype-environment correlation

3) trait utility

4) rapid speciation

adaptive radiation is caused by

1) ecological opportunity (e.g colonization, extinction of competitors, innovation)

2) high propensity for speciation

ecology

study of how organisms interact with each other and their environment + distribution/abundance of species + structure/function of ecosystems

population

all individuals of a species in one place at one time

community

all species living together in one place at one time

ecosystem

all species + their non living environment

factors that determine species distribution (biggest to smallest filter)

dispersal, abiotic conditions, species interactions

lethal zone

portion of environmental gradient where species performance equals zero

ecological niche

combination of physiological tolerances and resource requirements of species

hutchinsonian niche

an ‘n-dimensional' hyper-volume in which each axis is an ecological factor important to the species

temperature is mostly a function of: 

latitude

what factors determine biomes

temperature, rainfall, and the seasonality of them

factors that influence rainfall

atmospheric circulation, currents, rainshadows

cell order (0-30, 30-60, 60-90)

hadley, ferrel, polar

intertropical convergence zone

the zone of rising air near the equator that creates the hadley cells

why does the itcz move more over asia

more land mass

doldrums and horse latitudes

areas of low wind at the equator and 30 degrees

roaring 40s

strong westerlies in S hemisphere due to low land mass

deserts are near

cold water currents 

critical max/min temp

temp where some critical function of an organism is lost

fitness is maximized when reactions occur at

optimum temp/osmotic conditions

poikilotherms

can’t regulate internal body temp

homeotherms

can regulate internal temperature

bergmanns rule

homeotherms are larger at higher latitudes

allens rule 

homeotherms have smaller appendages at higher latitudes

enhanced vascularization purpose

redistributes heat, useful for cooling (loss thru convection)

countercurrent circulation

helps conserve heat in cold environment organisms

whittakers diagram

high precip and high temp = high productivity

hypothesis about complexity

greater complexity arises form greater cooperation among previously independent units

selection acts at a specific level when there is:

variation across the level, units exhibit heritability, units have differential fitness

mitosis benefit for cooperation

reduces variation between units

meiosis benefit for cooperation

randomness prevents any parent lineage from outcompeting the other

single cell beginning benefit for cooperation

less competition initially

meiotic drive

biological process where one allele is biased in transmission because the biased allele prevents proper formation of the other allele

if a favored allele is bad at the individual level, an organism may:

evolve silencing “restorer” alleles

transposable elements

self replicating segments of DNA, separate from cell replicatio

how do genoomes not explode from TEs?

alleles arise that methylate DNA, balance between high level and lower level selection

3 methods that cells stay cooperative

1) starting from single cell
2) separation of germ cells + limited divisions in germ cells

3) tumor supressors

weed resistance can evolve through these 3 ways

1) pre-existing variation 2) de-novo mutations 3) gene flow

3 axis of adaptation probability model

mutation supply rate, wild type fitness, probability of adaptation

evolutionary toggling

once resistance evolves, stop taking drugs so that non-resistant strain takes over (cuz fitness cost), then reapply 

evolutionary rescue

the process where a population facing extinction due to environmental stress is saved by adaptive evolution

probability of evolutionary rescue depends on

population size, how much fitness was reduced, beneficial mutation rate

what mostly influences seasonality at high vs. low latitudes?

temperature vs. rainfall