exam 3

an independently evolving lineage

a term used in biology to talk about the distribution of a taxon limited to a small geographic area and which can therefore be found naturally in this place

closely-related, morphological similar group of organisms

closely related monophyletic group of organisms with unique derived characteristics (synapomorphies!!)

closely-related group of organisms that are able to interbreed and produce fertile offspring

evolutionary(genetic) differences between lineages
Mechanisms to preserve these differences

pre mating barriers
-These barriers prevent contact and/or behavior between lineages
post mating barriers
-These barriers prevent mating from resulting in fertilization

1. lack of common homogenizing gene flow
2. strong directional or diversifying selection

allopatry-different place(no gene flow)
sympatry-same place(diversifying forces greater than gene flow)

vicarience-splitting of species range into physically isolated areas
ex. differentiation of carribean and pacific shrimp after emergence of panema

dispersal-dispersal or colonization events(founder effect)
ex. drosophila in hawaii, different species on different islands

Selection in different environmental conditions in Monkeyflowers
M. cardinalis only attracts hummingbirds, M lewisii attracts bees. evolved from ancestor that attracted both to accomodate light conditions and pollinator availability.

female sensory perception in cichlids based on environmental light differences caused radiating evolution of male coloring

disruptive selection amplifies sympatric speciation
ex. ploidy differences in plant species cause "instant speciation". switch to new habitat/ resource availability can also do this just slower

flies grown on starch or maltose based medium for several generations. when placed back together mated with other condition much less

melting ice caps reuiniting polar bear species
lakes/ rivers connecting to unite fish

the evolution of stronger isolating barriers via selection

Occurs when a single gene influences more than one trait

interactions between 2 (or more) loci

fusion-two species merge into one(or one goes extinct)
formation of a new hybrid lineage-distinct from both parents
stable hybrid zone established-a balance between the local production of hybrids and their elimination by selection
reinforcement-evolution of stronger isolating barriers via selection

if the hybrid offspring does not have higher fitness, then the parents are wasting their matings

p drummondii allopatric populations resemble other species, whereas sympatric populations differ
reinforcement is shown in sympatric bc hybrid offspring have less fitness, thus are selected against.
(look over this again you were distracted when making it)

flowers turning from purple to red

1. A single ancestral population is split into two daughter lineages
2. Daughter lineages independently accumulate mutations
3. Populations are bought back into contact and individuals in different lineages hybridize
4. Hybrid breakdown results when derived (new) alleles from one lineage are incompatible with alleles in the other lineage against which they have never been previously co-tested during their history (i.e. they have new deleterious epistatic interactions).

Xmrk2 gene in playfish
controls pigmentation, misregulation leads to melanoma

selection

post is never directly selected against, pre is
postzygotic involves epistatic interactions, pre rarely does

species can evolve rapidly
conditions that favor diversification arise continuosly
there has been a vast amount of time elapsed since the origin of earth

ecological controls-adaptive radiations are associated with novel selective conditions (new niches)
endogenous controls-phenotypes that faciliate speciation

mustard leaf beetle showed different mate preferences by different plant upbringings

nectar spur evolution allowing specialization of new resources

new niches
antagonist coevolution with plant defenses
mating isolation from host plant switching

Regions that are occupied longer tend to have more species
ranid frogs show much higher species count with higher time

there is a difference in speciation between temperate and tropic regions
molluscs show much higher diversity closer to 0 latitude line

lower latitudes have had longer occupancy due to saftey from glacial flooding

The ‘life history’ of a species is their lifetime pattern of
resource allocation to fundamental biological activities,
including growth, reproduction, and survival

ecological-Death due to extrinsic factors such as disease, predation, [and accidents]
physiological-Death due to intrinsic factors such as physiological and cellular damage, lack of repair, and so forth

intrinsic constraints-Death persists because of a fundamental constraint on the ability of selection to further act against it

rate of living-aging/senescence is caused by the inevitable accumulation of cellular damage (above what can be repaired) due to toxic metabolic by-products
-evidence is not in favor, metabolism is not standard to lifespan across species
telomere degredation theory-cells degrade as telomere length shortens
-some evidence in favor, but not completely
cellular mechs of persistence are a trade of with lifespan
-supported

Death persists because selection against it is opposed by other forces

mutation accumulation theory-deleterious alleles that cause late life senescence are relatively weakly selected, and can therefore accumulate via mutation/drift

alleles resulting in reduced fitness later in life may be advantageous earlier on or caused by multiple different loci
-alleles for longer lifespan in fruit flies have deleterious earlier-acting effects

within a reproductive bout,
selection will favor a clutch size
(# offspring) that maximizes the
number of surviving offspring

age at first reproduction(generation time) v life span
fecundity v survival
offspring quality v quantity
current reproduction v future reproduction

• Strength of extrinsic mortality
• Environmental resource quality
• Interactions with ecological antagonists (e.g. competitors)
• Predictability and/or stability of environmental resources

multiple lineages of hominins preceded the emergence of modern humans
modern human traits emerged stepwise via transitional forms

Associated with complex tool use
Capacity for symbolic thought
thicker metacarpel

out of africa supported by higher genetic diversity in african populations than non-african pops

mitochondrial dna inconsistent with history of interbreeding
hybridization must have occured outside of africa
hybridization was unidirectional, bc we don't have neanderthal mitochondria

higher amylase copy count in japanese and euro-americans show switch to higher starch diet consistent with domestication of cereals grains