Biological species concept

• ability to interbreed and produce viable and fertile offspring

Hybridization

• when two species can interbreed

• often happens in overlap zones

Behavioral isolation

• different mating behavior

  • The experiment when scientists showed a female bird the male bird’s mating dance at a normal speed(the female bird didn’t react any different), but when the female bird was showed the same video slowed down by a fraction of a second, she rejected it immediately.

  • quality of mating behavior( for example dances in birds) cannot be changed by practice because it is genetically programmed.

Temporal Isolation

• Difference in how often and when the females can become fertile

  • Mr. Schuyler talked about the different species of deer in North America

Mechanical isolation

• when mating can be attempted but not completed

  • many species of insects have a specific “lock and key” model

Gametic isolation

• Gametic fusion(syngomy) does not occur

• when chromasomes don’t match up, the gamete is terminated

  • different species of worms have different spots for the male and female parts, and if one species tries to mate with the other species, it will not work.

Hemaphrodite

• both male and female genitalia

• can do self fertilization

• at a genetic disadvantage

  • worms have both parts

post zygotic barrier

• when the zygote has happened but is not viable or fertile

• many die before reproductive age

• reduced hybrid variability

  • offspring of species a and species b

  • die before reproductive age

• reduced hybrid fertility

  • sterile when reproductive age is reached

  • think mules( they will live and survive to reproductive age, but most(99%) are sterile

• hybrid breakdown

  • when the first generation is viable and fertile, but next generations are not

Modes of speciation

• Allopatric speciation

  • 2 different species after they were separated and put back together

  • branching on a cladogram

    • wolfs in the u.s vs wolfs in Europe(before pangea)

• Sympatric speciation

  • auto/polyploidy

  • never has been an allopatric population

Sympatric vs allopatric population

• allopatric population

  • cannot reproduce if put together

• sympatric

  • two groups are put back together and can reproduce

  • still the same procedure

Ring species

• forms a loop around a geographical location

• allopatric speciation can occur

  • think of the salamanders around a valley(too fry for salamanders to go through) that got separated from each other and came together a different species

adaptive radiation

• changes occurring spreading

• evolution happens as the environment is changing(adapting as its moving from the start)

• can become a ring species

  • fruit flies in the hawaian islands

polyploidy

• nondistjunction(chromosomes don’t separate properly during meiosis)

• extra chromosomes where hey aren’t meant to be

  • down syndrome

  • many modern crops

• much more common in plants b/c they can actually benefit from extra chromosomes

  • new variations help adapt to environments better

autopolyploid

• potential method where a new species could evolve from from 2 organism of the same species

• all chromosomes are doubled

allopolyploid

• 2 organism from different species

• one has a meiotic error while the other one doesn’t(extra chromosomes)

• many errors slide past the error detector(?) so the zygote could survive

How would you unisolate an allopatric population?

• fish in lake Victoria cannot mate together(2 Sep species)(behavioral isolation)

• no geographical isolation

• they have different color skin

• how you could unisolate them

  • put a filter over the light(in a tank) to make the fish colorblind

  • if they mate and produce viable and fertile offspring, they are technically the same species, but not according to the biological species concept

General info

• evolution is not goal oriented

Absolute dating

• radioactive decay(half life)

• cannot get to zero

Pangea

• end of paleozoic era

• increased competition

• ocean space increased, but lower sea level

  • shallow organisms went extinct

mid - mezozoic era

• pangea started to separate

• founder effect(genetic drift)

• explains current distribution of organisms

  • marsupials

permian period

• destroyed 90% of marine animals

cretaceous period

• 65 mil. years ago

• destroyed 50% marine life

• destroyed many plants and animals(dinos)

• there is evidence of the asteroid b/c of iridium, which isn’t and element native to earth

  • it is on the layer with all the dinos fossils

  • we know where the asteroid struck(the landscape proves it)

• in some areas there was inc. temp, and other areas Dec. temp

phylogeny and systematics

• words mean interpretation of systematics and inferring common ancestry

• systematics

  • binomial nomenclature

  • genus & species

Cladograms

• phylogenic trees inferring common ancestry

• “the easiest solution is mostly correct”(until proven otherwise)

• out-group

  • extreme difference but has a commonality

  • like a backbone

Molecular clock

• junk DNA - mutations occur on a regular basis

• how long ago there was a common ancestor

Evidence AGAINST evolution

• fossil evidence and molecular evidence counter each other

  • BUT! less than 1% of 1% of organisms that died become fossils

Phylogenic fuse

• nature hates a vacuum(void)

  • something will fill the void

• mammals filled the void(Niche)(?) when the dinos went extinct

  • available recourses