EvoDevo Flashcards
Describe the Theory of Transformations. What effects do we see and how can we explain the observations of this theory? What do we know genetically, anatomically, and give examples!
Species differ mainly in their geometry, the developmental trajectory of the same building blocks.
- We can observe allometry (the growth of body parts at changing proportions). Differing timing of
regulatory development through heterochrony occurs through regulatory genes (how long a gene is
turned on, how soon it is turned on, and the rate or response strength of a signal).
- Examples: Shark pelvic fin genes in male sharks are turned on longer by exposure to testosterone,
developing into claspers
What are our two examples of Hox genes in fruit flies?
Antp: antennae expression
Ubx: Abdomen segments
What do we call a signaling molecule that changes cell differentiation/expression based on concentration of the signaling molecule? What model refers to the differing concentrations in causing differential expression/development? Describe an example of a developmental process that follows this model
Morphogen, the French Flag Model describes this phenomenon.
- In vertebrate limb formation in the limb bud, shh acts as a morphogen that is excreted from the
Zone of Polarizing Activity, its different concentration results in the different fingers growing from pinky to thumb.
What other process did we learn about in the limb bud during embryogenesis?
Apical epidermal ridge secretes Fibroblast Growth Factor inducing evagination of the limb bud Pax6: regulates eyeball expression
Talpid2: suppresses shh teeth expression in birds
Gremlin: blocks apoptosis of toes in ducks
What is a species concept? Name/describe three. What are their limitations?
Morphological: species defined by their morphological characteristics, individuals within a species look the same
- Biological: species defined by successful interbreeding
- Mate Recognition: defined by recognition of potential mates as being compatible. Birds with
different songs will not interbreed
What are our two major forms of speciation?
Allopatric: Speciation following geographic isolation. What are two ways they can become geographically isolated?
- Migration and vicariance (physical separation such as mountain, river, glaciation, sea level change)
Sympatric: Divergence from a genetic polymorphism. When individuals from same species diverge, reproductive barriers can arise. What kind of selection can result in this?
Name and define the two major types of reproductive isolation. Give examples of how each works. How does this relate to hybridization?
Prezygotic: Barriers to reproduction that prevent a zygote from being formed. 5 types? - Geographic, temporal, behavioral, mechanical, gametic
Postzygotic: A zygote is formed but either the zygote is not viable or the adult is not viable and/or fertile.
Describe and/or draw how a ring species complex forms. What is occurring in populations that are
connected around the ring compared to the populations that are connected at the furthest end of the ring?
Populations form a ring around geographic barrier. From either side of the original end, gene flow is occurring and the populations are reproductively compatible but show increasing genetic difference going down either side. Gene flow is not occurring over the geographic barrier. On the furthest end where the two sides of the ring have met again, these populations are not geographically isolated but are reproductively isolated
Describe three different rates of speciation and how they differ.
Stasis: Speciation not occurring, genomic evolution is. Long term stable environment
- Punctuated equilibrium: General equilibrium with speciation events. Persistence of ancestor
- Gradualism: Modest selection and variation (Coelacanth)
What is a mass extinction and what are the two we learned about in class? Which one was bigger? What is the significance of extinctions and mass extinctions? What could they tell us about how humans are affecting the environment?
- On a global scale, many more species go extinct than normal in a short period of time
- Permo-triassic/End-Permian/Great Dying: 250 mya, significant volcanism introduced much
more CO2 and SO2 into the atmosphere causing anoxia, ocean acidification, and global
warming. Largest known extinction event with - K-T/End Cretaceous/Cretaceous-Paleogene: 65 mya, asteroid hit earth with huge impact
and impact winter, ecosystem collapse from plant death. End of dinosaurs.
Extinctions open the door for new species and new macroevolutionary trends. End-permian made way for age of dinosaurs, K-T made way for mammals.
These events give us evidence for the effects of introducing greenhouse gases, changing the climate, and significantly altering ecosystems (ie widespread plant death)
What do we call features in organisms that are unused and fading away? Give some examples. What do they tell us about that trait and about evolution?
- Vestigial traits. Show that direction of evolution can change, traits that are no longer useful or are negative get selected against but not necessarily eliminated entirely.
- Examples: snake and whale hind-limbs, human pilomotor reflex, appendix (sorta, coccyx)
Evolution as a theory has predictive power. What’s an example of evolution being used to predict the existence of an organism?
Tiktaalik: Devonian fish→land-dwelling tetrapod predicted before fossils discovered
What does biogeography show us about organisms? What are examples of observations of biogeography
- Pattern of distribution reflects pattern of relation
- Wallace’s Line: Alfred Russel Wallace observed stark line separating Australia/New
Guinea/further East fauna (marsupials) from rest of southeast Asia (placental mammals). 50
million years of ocean separation! - Other examples: Galapagos finches and Drosophila in Hawaii, ratites distributed among broken
up Gondwanaland continents,
Demography
Study of population growth
Define resource. What type of resources have we talked about?
- Any environmental factor that an organism uses directly or indirectly
- Abiotic, biotic, expendable, nonexpendable
Density vs Dispersion
Density is # of individuals per unit volume,
Dispersion describes patterns of distribution within a species range
What are density dependent and independent factors?
- Density dependent: Typically biotic - parasites, predators, competition
- Density independent: Typically abiotic, like catastrophic events or pollution
What does a life table display and who does it follow?
Follows a cohort over lifespan, measuring things like survival and death rates, fertility (number of offspring produced per individual)
Draw and explain the three survivorship curves with an example for each
What are differences in life history traits that we expect from typical r vs K selected species? What are advantages and disadvantages?
Remember: r for rapidly reproducing
- Fecundity: Number of offspring produced, higher in r
- Time to reproductive maturity: younger in r
- Parental investment: less in r
- Lifespan: shorter in r
- Size: larger in K
- Population Dynamics: More stable in K
r: More successful with rapidly changing environments, less parental investment, but young are more vulnerable
K: More successful in more competitive niches, offspring more protected/nurtured/even taught, but high parental investment, loss of an offspring more detrimental
Think of some examples of typical r and K selected species, and then a species that shows more mixed or intermediate traits
What do r, K, N, and dN/dt represent?
- r = intrinsic growth rate
- K = carrying capacity
- N = population size
- dN/dt = the rate of population increase/growth at a given N.
Per capita growth:
The amount of population increase per individual
Total Growth
Total population growth. Multiply per capita growth x N
Community
Assemblage of all organisms close together enough for potential interactions.
