bio exam #2

genetic drift

any change in allele frequency in a pop. that occurs due to random change (not a mutation)

what are the 2 ways genetic drift can happen by?

1. random removal of organisms from breeding pop.

2. founder effect: movement of a small number of individuals from a given pop. to a new location where they start a new pop.

what is bottle neck effect?

third cause of genetic drift, where a major disaster occurs and randomly kills almost all individuals in a pop.

side effects of bottle neck effect

small number of survivors, reduced genetic and allele diversity

microevolution

overtime small changes accumulate, can lead to formation of new species, which is macroevolution

morphospecies approach

using physical appearance to define a species

issues with morphospecies approach

1. sexual dimorphism: females and males look different from one another in a pop.

2. cryptic species: 2 or more species that are identical

3. polymorphic species: members of that same species that look different and can breed sucessfully

biological species concept

ernst mayer, defined species as groups of actually or potentially interbreeding natural pops. that are reproductively isolated from all groups

reproductive isolation

isolation of a pop. caused by something that blocks reproduction

issues of reproductive isolation

1. cannot be used by asexual organisms

2. cannot be used by self-fertilizers

3. cannot be used by organisms only known from extinct fossils

phylogenic species concept

based on the evolutionary history of individual populations, starts with a common ancestor that other pops. have descended from

speciation

production of new species starts with genetic isolation, then pops. begin to diverge genetically through natural selection, mutation, lack of gene flow, genetic drift

pre zygotic isolation

before the zygote forms, mating cannot occur

post zygotic isolation

after the zygote has formed

mechanical isolation (pre)

physically impossible for breeding to occur, male and female reproductive parts do not match up

lock and key issues (pre)

body size must match, and some organisms have diverse penile shapes

habitat isolation (pre)

organisms live in same location but ecological differences prevent mating the

behavioral isolation (pre)

organisms that live in the same location, but behavioral issues prevent breeding (songs, calls, ritual ships)

temporal isolation (pre)

breeding periods of 2 species occur at different times, zero potential for breeding

isolation by prevention of gamete fusion (pre)

something prevents sperm from fertilizing the egg

sperm-egg incompatibility (pre)

something prevents sperm from penetrating egg, usually from incompatibility of sperm heads

hybrid inavalibility (post)

accumulation of genetic issues or differences from mis-matched sperm eggs causes offspring to die soon after birth

hybrid infertility (post)

offspring produced of closely related species survived to adulthood, but they are sterile or infertile

partial isolation

individuals that breed with members of other pops. frequently have low to no reproduction (fitness)

allopatric speciaition (general modes of speciation)

when pops. are seperated geographically, breeding and gene flow are impossible separated

through dispersal (general modes of speciation)

pop. splits, joins with new pop. in a new location (remain separated, isolation, to genetic divergence, to speciation)

vicariance

a change in habitat changes the pop. or splits into new pop.

causes of vicariance

volcanoes, continental drift, river flow changing, roads installed

sympatric speciation

pop. lives in the same area but there is no gene flow

sympatric speciation cause

mutation, chromosomal event

chromosomal event

change or difference in chromosome number btwn parents and offspring

autopolyploidy

change in chromosome number in self fertilization in hemaphrodites (male and female reproductive parts), leads to errors in gamete production

cause of autopolyploidy

external events, something alters the breeding habits or habitats of individuals

allopolyploidy

individuals from two similar species that interbreed

tetraploid vs diploid

offspring with 4n vs 2n (results from autopolyploidy)

effects of allopolyploidy

prevents breeding, to no gene flow, to isolation, to divergence, to speciation

strong host specificy

always breed on same species of plant (courtship behavior)the

what happens if an external event causes strong host specificy to fail?

habitat isolation to no gene flow, to genetic divergence

adaptive radiation

single species that rapidly evolves into several descendent species

adaptive radiation by ecological opportunity

• occurs when intense competition for resources arise

• species involved must have existing variation

• different species have different growth forms

• today all species share a common ancestor, rapid speciation rates, and diversified ecologically and physiologically

what does adaptive radiation require?

significant trait variation and selective pressure

adaptive radiation when new traits evolve

• can be caused by physiological, morphological, or behavioral changes

• driven by mutation

• new trait may allow organisms to use new food sources or new habitats

altered reproduction

new models of reproduction and pollution, occurs in flowers

causes of altered reproduction in flowers

• altered distribution of plants

• colonization of new habitats with successful reproduction

• increasing likelihood of new pollination (new shape, color, odor)

extinction

can alter speciation, rapid large reductions in number of species alive

human driven extinction

lose of species caused by humans, for example deforestation

phylogenetics and history of life

associated with how we describe species diversity and determining evolutionary relationships among organisms

what issues can arise with naming organisms?

• everyone names things differently

• can be named by physical characteristics

• can be named to resemble different organisms

• can be named by the habitat they are found in

• can be named by personal experience or cultural refrences

binomial nomeclature

species named by their genus + species

systema naturae

written by carolus linnaeus, defined naming species

hierarchy nomenclature

kingdom, phylum, class, order, family, genus, species

carl woese

added domain above kingdom

phylogenetics

system used to organize organisms through hierarchies

synapomorphies

shared characteristics between organisms

Based upon the shared characteristics that this phylogenetic tree is built upon, are Canada Geese more closely related to Goldfish or Chimpanzees?

chimpanzees

Using the letters on the appropriate bars, what is the most complete listing of traits that Rattlesnakes and Chimpanzees share?

A, B, C

While exploring the wilds of Siberia, I discovered a new bird called an “OBOE HERON”.  The oboe heron has traits found at bars A, B, C, and D.  Where would you place this animal on the phylogenetic tree above?  

with the canada goose

Choose all organisms from this phylogenetic tree that share the "warm-bloodedness" trait (bar D)

canada goose, black squirrel, and chimpanzees

Based upon this phylogenetic tree, choose all traits below that are shared by mammals (black squirrels and chimpanzees on this tree).

backbone, warm blooded, lungs, hair, amniotic eggs

The backbone is a trait shared by all organisms on this phylogenetic tree

true

prokaryotes

most abundant life forms, include bacteria and archaea, date back to 3.5 million years old, earliest are cyannobacteria

archaea

very simple, no pathogens, have symbiosis

primary extemorphies

associated with extreme abiotic conditions, classified based upon where we find them and the roles that they play

thermophiles

associated with extremely high temps, growth temp between 140-175 F

acidophiles

associated with extremely low pH levels, always below 2, found in bogs, forests, and foods like yogurt and sour cream

halophiles

found in extremely high salt levels , grow at 35-45% salt environments, found at saline lakes, and foods like kimchi

methanogens

noted methane producers, found in areas like wetlands and swaps, used as energy sources

bacteria

prokaryotes that lack membranes, also have huge diversity

gram-staming

divides bacteria by physiology and cell structure, shows positive and negative bacteria