Studied by 19 people
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?
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
adaptations for climbing and other locomotions
opposable thumbs
stereoscopic vision (binocular)
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.
Note 
Flashcard (80)