Evolutionary Bio Prelim #2

Adaptations and Speciations 3

Two-fold cost of sex:

asexual organisms can multiply faster and don’t rely on other organisms 

• Asexual grows at a rate of 2^n

  • Doubles EVERY generation

• Sexual can only produce 1 offspring for each reproduction

Costs of sexual reproduction:

• Requires finding an appropriate mate

• Parents are less related (0.5 vs. 1)

• Risk of contracting sexually transmitted diseases

Recombination

formation of new allelic combinations in offspring. Occur during meiosis via the cross over between homologous chromosomes (in eukaryotes)

• Genetic exchange can occur in bacteria but the recombination is basically just reproduction

Muller’s Ratchet

• The entire genome in asexual lineages is passed down

  • Deleterious mutations can accumulate

  • Results in genetic load - reduction with selective value compared to if all genomes had favorable genes

The Red Queen Effect:

 when a trait is ideal there is RAPID increase in that population, but when that population is too high competition is massive, causing a crash. 

sexual selection

• Form of natural selection which results from differential reproductive success among individuals

• Aka individuals that possess trait that help them to reproduce WILL be favored by sexual selection

sexual dimorphism

• A phenotypic difference between the male and female population

  • Can differ in:

  • Behavior

  • Physiology

  • Morphology (color,size, weapons)

• Body size

  • Male sea lions are larger

  • Same size in gre mouse and lemus

  • Females larger in great horned owls and anglerfish

operational sex ratio

• The ratio of males ot females available for reproducing at any given time

  • Garter snake: 64:1 males to females

  • Results in a “male biased” operational sex ratio 

    • Stronger sexual selection on males

Operational sex ratio under male-biase

• Males: invest in fertilizing eggs (many more males than females will not be able to mate at all)

• Females: not limited by the ability to mate

  • Can choose good mates

operational sex ratio under female-bias

• Females:invest in attracting mates

• Males are not limited in the ability to mate

  • Invest in choosing high quality mate

  • Take care of offspring 

  • Wattled Jacana

intrasexual selection

• Mating competitions

  • Usually males compete amongst males

  • Fights get violent if there is a big male-biased ratio

• Post-copulatory intrasexual competition

  • Sperm from multiple males compete to fertilize the same egg

  • Aka sperm competition

    • Larger testes, more sperm

1. Produce a lot of sperm

2. Remove sperm that is already there

   1. Fruit flies have spikes that can remove sperm that was previously there

3. Mechanisms that prevent sperm from being addd later

   1. Fruit flies seminal proteins make the females want to breed less later

intersexual selection

An individual selects their mates based on characteristics exhibited by the oppositve sex

senescence

decline in performance while aging

antagonistic coevolution

dynamics between competing specios or traits, where adaptations in 1 party drive counter-adaptations in another

• predatory-prey

• host-parasite

Adaptation and Speciation 4

phenetic vs. biological species concept

Phenetic Species Concepts

• Use morphological traits to define species 

  • Are readability observable

• Species: the smallest possible groups whose members are descended from a common ancestor and who all possess characteristics that distinguish them from other groups 

  • Species is a tip on the phylogenetic tree

  • Limitation: relies on having an accurate phylogeny 

Biological Species Concept

• Species: a group of actually or potentially interbreeding populations that are reproductively isolated from other groups

  • Advantages:

    • No trouble with different morphs within a species/cryptic species

    • Does not requiere human interpretation of morphology/ detailed phylogenetic info

  • Disadvantages:

    • What is meant by potentially interbreeding?

metapopulation

• a group of spatially separated populations of the same species that exchange individuals/genes to at least some degree

2 methods for new species arising

• Barrier to gene flow

1.Georgraphical barriers (extrinsic)

• Mountains, rivers

• physical barrier 

• Allopatric speciation, peripatric speciation

2.Reproductive Barriers (intrinsic)

• Mating preferences, hybrid incompatibilities 

• Evolutionary divergences which prevent gene flow

• Parapatric speciation, sympatric speciation

speciation

the formation of new species

allopatric (allo=other, patric=place)

occurs when populations are separated by an extrinsic geographic barrier 

sympatric (sym=same, patric= place)

• Some individuals begin to exploit a new niche, and mate only with other who do the same

parapatric (para=beside, patric=place)

• Occurs when species are spread out over a large geographic area, but mate only with those that live close to them

• continuously distributed pop

  • Poluted soils vs. good soils may deviate into 2 species

peripatric (peri=near, patric=place)

small number of individuals are separated from the main population by migrating

vicariance

• The formation of geographic barriers that separate a population 

  • Ex: shrimp species on either size of central america used to be 1 species (formation of Panama separated gene contact)

gametic incompatibility

1. Sperm cannot feritlize egg

   1. Lack receptors on egg for fertilization

premating barriers

1. Behavioral isolation

   1. Fireflies - different flashing patterns amongst different species

2. Ecological isolation

   1. Habitat 

   2. Temporal

      1. Apple maggot fly 

         1. Some maggots who laid eggs on apples started breeding earlier in the year

         2. Became more temporally separated (formed new species)

   3. Pollinator isolation

3. Mechanical isolation

   1. Differences in male genitalia 

prezygotic reproductive barriers

1. Copulatory behavioral isolation

   1. Species-specific behaviors during copulation may be necessary for fertilization

      1. E: tapping behavior in Orchid Mantis

         1. Will be rejected if tapping is incorrect

2. Gametic isolation

   1. Sperm cannot feritlize egg

      1. Lack receptors on egg for fertilization

postzygotic reproductive barriers

1. Intrinsic

   1. Hybrid indiviability

   2. Hybrid sterility

      1. Hybrids are unable to reproduce (mules)

2. Extrinsic - hybrids are less fit in some environments

   1. Ecological inviability

   2. Behavioral sterility 

      1. Can’t obtain mates but are able to reproduce

      2. Ex: hybrid grasshoppers can’t make the correct rubbing signal

what does reinforcement do to with natural selection?

Natural selection leads from postzygotic to prezygotic isolation, and the formation of new species through reinforcement

fusion

• If divergence results in no prepzygotic or postzygotic isolation, and populations that come into secondary contact interpreed, they can become one species

primary hybrid zone

• Population A and Population B have no physical barrier separating them

secondary hybrid zone

• Population that have diverged in allopatry come back together

  • Have extrinsic separation that disappeared

• Usually have much less offspring

  • Reinforcement AGAINST hybrid population

    • Selection against hybrid offspring increase separation

Macroevolution 2

standing diversity

Standing diversity12 = standing diversity11 + origination - extinction

• Each line represents the time where a taxon existed 

• Count the number of taxa present at the beginning of stage B

origination

species that appeared during the current stage

2 types of extinction (bacground rate and mass extinction)

Background rate: 

• “Ordinary extinction” with a variety of causes

  • Changing climate

  • Loss of food resource

  • Predation, disease, competition 

Mass extinction:

• Statistically significant departure from background rates

• Involve the extinction of many clades

in a graph it is the last appearance of that species in that stage

adaptive radiation

 rapid diversification into many forms over a short period of time

• Mass extinctions and/or background extinctions can open up niches to allow other organisms to evolve. However, rapid evolution into many forms, or adaptive radiations, doesn’t only occur because of extinctions

  • Example: Darwin’s finches on the Galapagos Islands

    • Many new habitats, which allowed for rapid evolution

    • Honeycreepers on Hawaiian Islands

      • Evolved to occupy new niches for volcanic activity

      • 50 in 5 MY

character displacement

• Competition between species for a resource or niche species for a resource or niche drives evolution of different traits. 

Cambrian Explosion

541 MYA

• rapid diversification of life forms

Sepkoski’s curve

• Marine invertebrates families

• X-axis is periods 

• Mass extinctions are A-E

Sepkoski’s curve extinction A

• 60% 450 MYA

Sepkoski’s curve extinction B

70% of species 375 MYA

Sepkoski’s curve extinction C

• Permian extinction

• 96% of species 250 MYA

• Large volcanic eruption in Siberia 

  • Released a lot of CO2 and methane 

  • Characters:

    • Increase in temp 

    • Increase in CO2 in oceans

    • End of the Trilobites

      • Marine arthoropods 

  • Marks the boundary between the permian and the triassic 

Sepkoski’s curve extinction D

• 75% of species 200 MYA

Sepkoski’s curve extinction E

• Kpg extinction (Cretaceous-Paleogene extinction) 

• Occurs at the end of the Cretaceous and the beginning of the Paleogene

• 75% species 65 MYA

• Massive asteroid hit near the golf of mexico

• Killed all non-avian dinosaurs

  • Extinctions:

    • Pterosaurs, marive reptiles, many insects, plants

    • Opened up many niches for birds to radiate with the loss of dinosaurs

anagenesis

mode of evolution; slow evolution

cladogenesis

stasis followed by rapid evolution (fast tempo)

punctuated equilibria

1. Morphological change occurs relatively rapid associated with splitting of lineages (cladeogenesis, typically through allopatric orperipatric speciation)

2. followed by long periods of stasis

stasis

no net change is fossil reccords

sympatric speciation

1. Some individuals begin to explot a new niche, and mate only with others that do the same

   1. Certain food ex.

Biodiversity 3

glaucophytes

• unicellular algae at the base of the plant clade

• Only have asexual reproduction

“Green Algae”

form a polytomy and is sister to land plants

• can be uni or multicellular

Red algae

• Marine

• Do not have chlorophyll b or starch (not green plant)

• Make more chlorophyll A 

• Sister group to green plants (which have chlorophyll b, and starch) 

Green Plants

• Synapomorphy = chlorophyll b and starch as storage protein

• Largest clade

• Have chlorophyll b and starch

  • Permits photosynthesis

  • Extends wavelengths that can be absorbed (effective at different wavelengths) 

  • Allowed plants to go from aquatic to land

challanges of going from water → land

• Desiccation

• Physical support

• Movement of fluids/nutrients without free flowing water

• Protect gametes

• Increased UV radiation

Land Plants - characteristics

• Waxy coat (cuticle) to help prevent water loss

• Retention of embryo

  • Latex cover

  • Seeds

• Plant body evolved to have phloem and xylem 

  • Xylem allow for movement of water

  • Phloem is movement of nutrience

  • Stomata allow for water and gas exchange

Generational alternation in Land Plant

• 2n sporophyte stage produce haploid spores (n) gametophyte stage 

  • Will fuse again during fertilization to form a diploid zygote 

• The fertilized egg will develop into a diploid sporophyte

nonvascular land plants

characteristics:

• Gametophyte is large and haploid

• Sporophyte is small and attached to gametophyte

• non-seeded

  • need water for fertilization

liverworts

• low to the group

mosses

• Simple fluid-transport (not considered vascular)

• Larger and more complex than liverworts 

Vascular Plants

1. large sporophyte

   1. Lycophte, ferns, seed plants, gymnosperms, angiosperms

2. Unified by having phloem and xylem 

3. Spend most of their life in sporophyte generation 

Plants spend longer and gets bigger in sporophyte stage than in gametophyte stage

1. sperm is carried in pollen grain

Lycophytes

• Have a microphyll (synaporphy) with 1 vein (simpler leaves)

• Has a vascular system

• Dominant in Carboniferous period 

• LARGE sporophyte

Ferns

• Megaphylls - more complicated leaves

  • United with seed plants for megaphylic (synapomorphy)

• LARGe sporophyte

Seed Plants

• sperm is carried in pollen grain

• type of vascular plant (large sporophyre, small gametophyte)

• synapomorphy = seed

2 types:

• gymnosperm

• angiosperm

Gymnosperm

• naked seed

reproduction

1. Pollen grain lands on female gametophyte (cone) and males pollen tubes

2. Pollen tubes deliver sperm that fertilizes the egg

3. Ovule develops into seed

   1. Resistant to drying out and has nutrients

Angiosperm (Flowering Plants)

• Sporophyte plant produces spore that are haploid

  • Grown into multicellular male and female haploid gametophytes

• Flower is part of the sporophyte plant + it is diploid

• Part of the carpels on the flower is the ovary

  • Also sporophyte tissue

• In the ovary are the ovules 

  • Also sporophyte, will produce the spores that become the female gametophyte 

  • Contains some haploid gametophyte tissue + haploid egg cell 

• Some cells of the pollen grain become the pollen tubes while other are the sperm

• Pollen make pollen tubes 

  • Will deliver sperm to egg 

• This is double fertilization 

  • 1 sperm fert. The egg

  • The other sperm fuses with the 2 nuclei to make a triploid endosperm 

    • Extra nutrients for the embryo

stomata

pores on the leaf that allow gas and water exchange

chlorophylls a and b

a → in red algae + green plants

b→ in green plants

• extend wavelengths that can be absorbed

haploid vs. diploid

haploid → n

• most meiosis to fertilization

• includes gametophyte

diploid → 2n

• post fertilization (zygote) to meiosis

• includes sporophyte

sporophyte

asexual (and usually diploid) phase

• produces spore from which the gametophyte arises

• dominant in vascular plants

spore

• becomes the female gametophyte

• holds some haploid gamtophyte tissue + haploid egg cell

gametophyte

• usually 1n (haploid)

• produces gametes through mitosis which will fertilize to make a zygote

gamete

(egg/sperm)

• mature haploid male/female germ cell ready to unite with another to form a zygote

microphylls vs. megaphylls

microphylls

• synapomorphy for lycophytes

• 1 vein (simpler leaves)

megaphylls

• more complicated leaves

• united with seed plants for megaphyll (synapomorphy)

enclosed seeds

seedds with hard flesh around it in angiosperms

• protects seed

• flowering plants

naked seed

• gymnosperms

• non-flowering

• not enclosed by a cone or fruit

• rely on wind for pollination

xylem vs. phloem

xylem carries water through vascular system while phloem carries nutrience and waste 

pollen

male gametophyte

• Some cells of the pollen grain become the pollen tubes while other are the sperm

• Pollen make pollen tubes 

double fertilization

• 1 sperm fert. The egg

• The other sperm fuses with the 2 nuclei to make a triploid endosperm 

  • Extra nutrients for the embryo

stamen

male fertilizing organ of a flower

• includes pollen anther and a filament

anther

part of stamen containing the pollen

ovary

• part of the carpels on the flower or the sporophyte tissue (fruit)

• contains the ovules

primary chloroplast

cyanobacteria engulfed by eukarya

endosperm

• triploid biproduct of double fertilization

 arbuscular mycorrhizal fungi

• type of fungi

• Form mycorrhizae with 90% of plants

• Relationship

  1. Fungus gets photosynthate

  2. Plants get increased SA for acquisition of soil nutrients

Ascomycota

1. Ascomycota 

   1. sac/cup fungi

   2. Produce spores in an ascus

      1. When it bursts from pressure

   3. Ex: morels, truffles, most yeast/molds, most lichens 

      1. Yeast: any single-celled fungi 

         1. Model organism is brewers yeast 

      2. Lichens: usually ascomycete, photobionts, green alga and/or cyanobacterium

         1. Slow growth and complicated 

         2. Able to tolerate extreme conditions

 Basidiomycota

1. Club fungi

2. Produce spores on a basidium 

   1. Produces/discharge passively

3. Examples: rust, smut, mushrooms, brackets

   1. rusts/smuts: 

      1. Serious pathogens

   2. Brackets: on sides of live/dead trees

   3. Mushrooms:

      1. Fruiting bodies grow from undergroud mycellium 

“chytrids”

1. Paraphyletic group

2. Synapomorphy: flagellated gametes that is used to swim in water

   1. Only fugus with flagella 

   2. Famous for killing frogs

3. Can be uni or multicellular

4. Asexual and sexual reproduction

5. Mostly saprobic (eat decaying matter) but a few are parasitic 

Dikarya

1. Dikarya

• Synapomorphie: dikaryon stage (2 nuclei), septate hyphae

• Reproduce sexually (2n+) and asexually (n)

  • For sexual reproduction there is no distinguisting characteristics between male and female

  • A combination of 2 genetic strains 

• Have septate hyphae

  • Can control movement of cytoplasm and organelles

• 2 major groups

1. Ascomycota 

2. Basidiomycota

fungi

• United with animal and choanoflagalletes in the opishtokonts by the syampomorphy (single posterior flagellum)

• fungi bodies

  • Tubular filaments of the body of fungi (called hyphae) that allow organic materials and organelles to pass)

  • A large collection of hyphae is called mycelium 

• Synamporphies: 

  • Chitin in the cell wall

  • Absorptive heterotrophy (form of nutrient acquisition) 

lichens

1. Lichens: usually ascomycete, photobionts, green algae and/or cyanobacterium

2. type of ascomycota

   1. Slow growth and complicated 

   2. Able to tolerate extreme conditions

Microsporida

One of the main groups of FUNGI

1. Small, unicellular parasitic 

2. Synapomorphy: reduced mitochondria, polar tube

3. Polar tube: infect host cell

   1. dangerous!

Opisthokonts

Clade including animalia, fungi, and Choanoflagellates

Saccharomyces cerevisiae

brewers yeast,

• type of Ascomycota, which is a type of Dikarya

absorptive heterotroph

synapomorphy of fungi

• secretes digestive enzymes to externally absorb nutrients

ascus

where ascomycota sac fungi produce spores

• burst from pressure 

basidium

where basidiomycota produce spores

• are produced and discharge passively

dikaryotic

• 2 genetically distinct nuclei within 1 cell

chitin

what fungal cell walls are made of

• also in the exoskeleton of bugs

hyphae

tubular filaments of the body of fungi

• allows organic materials and organelles to pass