Bio 1M03: Test 2

Sympatric Speciation

Sympatric Speciation

Speciation that occurs in one place. Populations live in same area (dont have to be physically isolated, can prefer diff habitats)

Can natural selection cause speciation when gene flow is possible?

Yes. In certain cases, natural selection can overcome gene flow and cause SYMPATRIC SPECIATION (don't have to be physically isolated, can prefer diff habitats)

How is distributive selection (extremes favoured) shown in the soapberry bug?

Some prefer to feed on different fruits and in response to that beak length shifts

Polyploidization

Genetic isolation created by formation of polyploid (+1 set of chromosomes) individuals, that can only breed with each other

Mechanisms of sympatric speciation

Distributive selection, polyploidization, autopolyploidy, allopolyploidy

Autopolyploidy

Polyploids have duplicate chromosome sets from SAME species, spontaneous genome duplication

Allopolyploidy, how does it happen?

Polyploids have chromosomes sets from DIFFERENT species (hybridization event followed by a chromosome doubling, keeps multiplying)

What is an example of an autopolyploid? What is the meaning of their polyploid?

Maiden Fern, which include diploid (2n), and when diploids self-fertilize tetraploids (4n) occur. **They can only breed with their own kind

How many geonomes are in a tetraploid individual? octaploid?

2 full genomes (4 copies each chromosome), 4 full genomes. (Their gametes will produce half of however many chromosomes they have)

What is wrong with triploids?

They often create gametes with the wrong number of chromosomes

What happens when diploid and tetraploid gametes breed?

a triploid

Polyploidization is more common in animals. T or F?

F. It is more common in plants (genome duplication during mitosis, which then goes through meiosis creates polyploids)

Why is polyploidization less common in animals?

Far fewer rounds of mitosis come before meiosis, plants self-fertilize way more, hybridizations occur more in plants

What happens when isolated populations come into contact? (4)

Populations may interbreed resulting in hybrids, homogenization where species erase distinctions through gene flow, adaptive introgression, development of hybrid zones

Adaptive introgression

Advantageous genetic variation is transferred from one species to another

Hybrid Zones

Where ranges of genetically distinct species overlap

Reinforcement

Selection for traits that isolate populations reproductively

What happens when hybrid fitness is typically low?

A strong natural selection against interbreeding

Assortative mating

Biased mating with other individuals with SIMILAR TRAITS (may be adaptive)

Can hybrids speciate? Eg?

Yes sometimes they can be more fit, Red wolves (part wolf, part coyote)

Which of the following is true regarding polyploidization? (a)Autopolyploidization is an example of sympatric speciation but allopolyploidization is an example of allopatric speciation (b)Polyploids are better adapted than diploids and therefore able to outcompete them (c)Gametogenesis in polyploids results in non- reduced gametes (gametes with the entire genome of the parent) (d) One reason that polyploidization is more common in animals than plants is related to the frequency that hybridization occurs (e) None of the above

(e)

On phylogenetic trees, what are the end (terminal) nodes?

Taxa (genes, populations, species)

What are polytomies on phylogenetic trees?

node where we don't know which of the taxa are most closely related. (if one node branches into 3 taxa we don't know which taxa are most closely related)

What's the difference between homology and homoplasy?

Homology is when traits are similar due to ancestry, and homoplasy is when traits are similar for reasons OTHER than shared ancestry (caused by convergent evolution)

Convergent evolution

When natural selection favours traits in different NON-ANCESTRY species due to similar ways of living

Synapomorphies

Novel trait that a clade of organisms possess, but others outside the clade lack

How do researchers estimate phylogenies?

Researchers analyze characteristics, maximum parsimony focusing on synapomorphies

According to this phylogenetic tree, are platypus eggs and komodo dragon eggs homologous?

Yes, they come from a common ancestor which are lost after their speciations

More Parsimonious

Fewer changes or fewer nodes to obtain the change

How can we tell if these hox genes are homologous?

Similar sequence, organization, expression patterns during development, similar function,

What is support for the "Whippo hypothesis"?

Gene sequences show that whales and hippos share SINE genes (parasitic DNA) that other artiodactyls don't have (synamorphies)

SINE genes

Short interspersed nuclear elements, parasitic DNA that inserts itself into different parts of the genome which is very unlikely to evolve and happen again

Cryptic Species

Indistinguishable biological groups that are incapable of breeding

What is DNA barcoding? Why is it useful?

Sequencing all species in world on a database, useful for assessment of biodiversity and a solution for cryptic species

Atavism

an ancestral characteristic that is lost but then re-emerges during evolution

Adaptive Radiation

Increase in number of species with a common ancestor

In situ (in position) diversification

Diversified on the Galapagos islands and came from a common ancestor, habitats did not let them overlap so not necessarily sympatric speciation

Anolis Lizards

Underwent adaptive radiation (small bodies vs larger bodies), ancestor dispersed -> evolved -> colonized into microhabitats. AND THEN ANOTHER ancestor dispered -> evolved into the same ecotypes

Species for species matching

seeing the repeated evolution of the ecotypes over and over

Wallacia region

Biodiversity hotspot, high concentration of species that occur nowhere else in the world

Where is there more frog species diversity Philipines or Sulawesi? Why?

Philippenes, their frogs can lay eggs in a gel sack (like the Platymantis frog)

What type of frog in Sulawesi has high diversity?

Fanged frogs

What was observed in the different parts of Sulawesi?

Different sizes of the same species, and different species in different parts of the country. Body size heavily correlated with micro habitat (fast moving water --> bigger body)

What are the different scenarios explaining why body sizes differ in Sulawesi?

1. EX SITU: could have happened somewhere else and frogs just dispersed independently 2. adaptive radiation: a single ancestor dispersed once, and then there evolved into different ecotypes through natural selection

How do frogs differ in reproductive ecology?

Internal/external fertilization, leaf nesters

Evidence for an adaptive radiation

Diverse and closely related species vary in useful traits

Trait variation is correlated with environmental variation, which evolved in situ

Species for species matching

Did fanged frogs undergo an adaptive radiation? How do you know?

Yes. Diverse and closely related species vary in useful traits, trait variation is correlated with environmental variation, which evolved in situ, species for species matching

Why could ecotypes re-evolve?

Regional adaption (wet vs dry conditions), and habitat fragmentation

Main clues for adaptive radiation in fanged frogs

-Repeated origins of pronounced variation in BODY SIZE as well as REPRODUCTIVE ECOLOGY. -Many more species than currently described -Patterns of biodiversity can identify biodiversity conservation priorities

Adaptive RadiationS

Instances of rapid diversification, depends on diet and other envrionmental factors

Biological innovation? What does it do?

When a new characteristic continues to evolve, allows ancestors to: -rapidly diversify -live in new areas -exploit new food sources -move in new ways

What reasons did adaptive radiation occur for Cichlid fish?

-Feeding -social behaviour variation -morphology (shallow waters)

What is a decoupled jaw system?

Occurs in fish to allow them to collect and process food easier. An example of an adaptive radiation

Extinction (mass and background)

B: level of extinction when mass is not occurring M: periods with extreme biodiversity loss (reasoning is ususally unclear)

How do background and mass extinction differ?

B: caused by normal environmental change, disease or competition M: caused by extreme, temporary and sudden changes. Causes extinction in RANDOM species

What does the shaping represent here? Timeline?

Each narrowing is a bottleneck effect, thick grey = amount of biodiversity. Top of graph = present

Impact Hypothesis? Evidence?

Imposes a meteorite struck earth 65 mya and caused the extinction of 60-80% of species alive. Evidence: MICROTEKTITES (hallmarks of meteor impacts) in rock layers and fish gills, peak of iridium content at that time

What did the extinction of dinosaurs do for mammals?

Created ecological opportunity for adaptive radiation of mammals, and allowed mammal evolution to grow

What is the greatest cause of extinction?

Humans

What is the difference between past and present Nile Perch fish? Why?

Can eat whatever, even other fish. They are much smaller now since their food sources deplenished

What happened when the Nile Perch was introduced into lake victoria?

• many cichlid species went extinct (some ate algae)

• algae content went up substantially, slows decomposition

• Slowed decomposition reduces oxygen content

• deforestation to cook the fish

• fish are now smaller and overfished

What do the boundaries between time eras represent?

Mass extinctions or major diversification events

Milestones in the Precambrian Era?

• first fossils of bilaterally symmetrical organisms

• origin of life

• first eukaryotes

• photosynthesis

Heterotrophic

Ingest other organisms

Cambrian Explosion

Diversification of animals, is documented by fossils. Many major lineages of animals appeared after the explosion

500 million years ago

Doushantuo Fossils

China, microscopic. Documented Cambrian explosion

Ediacarian Fossils

Australia, small and soft-bodied. Documented Cambrian explosion

Burgess Shale Fossils

British Colombia, diverse and large animals. Documented Cambrian explosion

What caused the Cambrian explosion? When did it occur?

Environmental: increased oxygen and ozone layer thickness Ecosystem Engineering: animals changed their environments (eg Bever making river into home)

Occurred 500 million years ago

What do Hox genes have a correlation with? Cambrian Explosion?

Number of Hox genes has increased morphological complexity. Could have been duplicated before and during Cambrian explosion, producing new body plans and appendages

Are hox genes the cause of all diversification?

Not necessarily, may have played a role but aren't a catalyst

What do colours and missing boxes represent?

Colours: orthologous genes (derived from common ancestors) Missing: means genes were lost in that species

What is a function of Hox genes?

They are TRANSCRIPTION FACTORS, regulators of animal development and trigger development of specific body parts

Define “Make another 2nd parasitic segment” in respect to hox genes and fruit flies

causes a pair of wings to develop into another pair of wings (this trait is in dragonflies as well from convergence)

Hox genes and non-hox genes act as _______ whereas others set up __________ that trigger biological cascades, and determine what characteristic that cell type ends up having

switches, gradients

Evolutionary Development

Transcription can turn on and off during evolution, changing where genes are on/off

How do gene cascades work?

A gene can activate cascades of genes that lead to the development of legs

Changing the expression domain will...?

Change the phenotype

Gradients of gene expression

Certain genes are expressed in different parts of different species (leads to segments in different tissue types)

What signals genes where to go and when to develop?

Mix of hox genes and gradients

T or F. Increased gene complexity = larger number of genes

F

Why is mutation of Hox genes important to humans?

Can be lethal

Truncation mutations

Hox genes disrupt development of brainstem and cardiovascular system, resulting in mental development delay and AUTISM

Mesozoic Era

First placentals and mammals, angiosperm development (flowers and fruit)

Cenozoic Era

mammal diversification

What differed between plants in the mesozoic era and now?

They used spores (less food storage) instead of seeds

What affect did angiosperms have on primate evolution?

Food/shelter source. Primates had to compete and evolve for angiosperm resources

4 main characteristics of primates

1. adaptations for climbing and other locomotions

2. opposable thumbs

3. stereoscopic vision (binocular)

4. large brains

Rosalind Franklin

One of the co-discoverers of the structure of DNA

Anthropoids

New world monkeys and old world monkeys and apes

In the monkey reward video, what do the monkeys demonstrate?

Cucumber monkey can recognize the sophisticated sense of justice

Early Hominin subsistence video

Chimpanzees work together in groups with specific roles while they hunt.

Late Miocene/Pliocene time primates moved where and why?

Into grassland habitat, and because the global climate was much colder in the past with less precipitation

Locomotion

Movement through space

What was the first evidence for adaptive locomotion?

Observed in hominoid fossils from the Miocene. Braciation, a movement in their shoulders for swinging from trees

What are 3 benefits of bipedalism?

• better for temperature (less solar radiation)

• leaves hands free for carrying objects

• Increased dependence of offspring, so makes it easier to care for them

Suspensory locomotion

arboreal species, whose locomotion consists of mainly swinging and brachiation. They have long forelimbs and fingers, very mobile joints and a strong pelvic floor

T or F. The origin of bipedalism has happened 1 time in primates?

T

What was observed about hominins in Africa?

There used to be more species in our lineage, hotspot of human evolution

When was the chimp-human split? What features did they have a mixture of?

Radioisotopes show 5-7 million years ago was when the most recent common ancestor lived. Ancestral and derived.