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BIOL 2600 Final Exam LATEST 2024/2025 100% ACCURATE
FALL-SPRING GRADED A+ (QUESTION AND ANSWER)
Meckel-Serres law Meckel added to scala naturae: he hypothesized that the developmental stages of the individual paralleled the evolutionary history of that species (development steps through each species that came before)
- hypothesized that embryos of organism step through the adult stages of species that preceded them von baers law
- Karl Ernst von Baer rejected both scala naturae and the Meckel-Serres Law.
- states that when comparing developmental stages of closely related species, general traits develop before the specialized traits that allows us to distinguish species from each other Haeckel's Theory of Recapitulation ontogeny is a precise and compressed recapitulation of phylogeny
- new species generated by adding something new to the terminal part of development
- today has been rejected
heterochrony study of the time in the developmental process at which a developmental trait is first expressed in a species, compared to other species what are the two categories of heterochrony
- changes to reproductive traits
- changes to somatic traits when might natural selection favour progenesis?
- progenesis is an accelerated appearance of reproductive traits in a species compared to its ancestor
- in especially harsh environments, where survival and reproduction decrease quickly with age, the acceleration of the appearance of reproductive traits - progenesis- might be favoured neoteny the later/ stalled development of somatic traits
MADS-box genes homeotic genes involved in determining which cells become:
- stamens
- carpels
- petals
- etc colinearity with hox genes, the position of each hox gene on a chromosome corresponds to the relative position of the body part that the hox gene regulates regulatory enhancer cis-regulatory element; a noncoding region of DNA that controls the spatial and temporal expression of nearby genes.
- Act as switches that turn genes on and off, affecting the amount of product (generally proteins) produced by a gene.
- A single gene can have numerous, independent regulatory enhancers associated with it.
paralogs homologous genes within a single species
- paralogs of genes involved in developmental pathways can create new developmental pathways, as over time, the two paralogs will undergo different mutations and so may follow different evolutionary trajectories gene duplication the establishment of multiple copies of genes within a genome paralogs can be maintained in a population for three different reasons:
- Duplicate genes may influence gene expression levels by increasing production of histones, ribosomal RNA, and other products
- Subfunctionalization: After duplication, paralogs may diverge because they divide the work initially undertaken by the original gene before duplication.
- Neofunctionalization: Duplicated genes may diverge, with one of them taking on a new, but related, function. species concepts
- Evolutionary Species Concept
phenetic species concept pros and cons
- can be used on extinct species - morphology from fossils
- can use genetic data in similar way
- doesnt include evolutionary history
- traits could be the same due to convergent evolution and NOT due to shared evolutionary history
- fails when within species variation is high or between soecies variation is low biological species concept Delineates species based on reproductive isolation
- Gene flow is the main determining factor to determine whether or not they are breeding and exchanging genes
- Quantifying gene flow is the way in which we can determine whether or not groups are reproductively isolated.
- extinct species, asexual species, hybridization events homeotic genes genes that determine the identity and positioning of anatomical structures segmentation genes
genes that are associated with patterning of the body scala naturae species ranked from lowest to highest with humans at top ontogeny the development of an individual over its lifetime ecological species concept delineates species based on niche
- Individuals cluster together based on their niche; these individuals are the same species.
- ESC focuses on ecological processes that allow two populations to coexist
- individuals of same species compete most closely with eachother
- pro = can be used for asexual species, possible for extinct species
- con = doesnt work well on species with different morphs phylogenetic species concept
last universal common ancestor
- phylogenetic studies cannot see beyond LUCA
- LUCA is not necessarily the first living thing Darwins "warm little pond"
- prebiotic soup
- soruces of energy capable of making prebiotics: lightening, cosmic rays, volcanic eruptions, earths internal heat. stanley miller and harold urey experiment attempted to recreate conditions of earth to test the plausibility of the prebiotic soup hypothesis
- Numerous common amino acids, such as glycine, alanine and valine were produced
- An analysis done years later with more sensitive equipment showed that the original experiment produced over 40 kinds of amino acids! showed that prebiotic molecules were likely present when life is thought to have evolved vesicles
small fluid-filled spaces enclosed by a lipid membrane maynard smith and szathmary hypothesized:
- Individuals give up the ability to reproduce independently, and they join together to form a larger grouping that shares reproduction
- Once individuals aggregate into higher-level groupings, they can take advantage of economies of scale and efficiencies of specialization.
- Aggregation and specialization facilitate changes in information technologies. Organisms develop new and increasingly efficient ways to acquire, process, transmit, and store information. evolution of the eukaryotic cell
- Eukaryotes have membrane-bound organelles: chloroplasts and/or mitochondria and a nucleus containing the genomic DNA.
- Eukaryotic cells are (generally) more complex than prokaryotic cells. Eukaryotic cells have complicated within-cell communication networks that :
- coordinate interactions among organelle, cytoplasmic elements and the nucleus
- Target the appropriate proteins and other resources to the appropriate substructures within the cell
germ cells vs somatic cells (by definition is not possible with single-celled organisms) The Costs of Group Living
- Competition - conspecifics compete for limited resources (food, mates, territory, etc)
- Cheaters - attempts to usurp resources from others
- parasites/diseases - pathogens spread more easily in groups three modes of speciation allopatric, parapatric, sympatric allopatric speciation in different places geographically isolated parapatric speciation in populations that are adjacent to each other
sympatric speciation in the same place allopatric speciation - two models
- vicariance model
- peripheral isolate model vicariance model one very large population subdivided into two large populations
- drift is unlikely due to large size of subpopulations; different selective pressures peripheral isolate model division of populations that are different sizes one large and one or more small
- founder effects and drift occur in small subpopulations; still different selective pressures
extinction all individuals of a species or taxa have died out leaving no living descendants extant a species that is still in alive some place in the wild extirpated a species that no longer exists in the wild in a specific area, but occurs elsewhere law of superposition fossils found lower in the strata are older than fossils closer to the surface endemic when a species is only found in one specific area
cladogenesis speciation occurs through branching events anagenesis speciation occurs through gradual modification of form without branching pseudoextinction the result of anagenesis (the ancestral species appears to be extinct) Obligate sexual reproduction only produce sexually obligate asexual reproduction only produce asexually environmental unpredictability model
anisogamy production of two kinds of gametes (egg and sperm)
- different sized-gametes are the root of sexual selection because they introduce the potential for selection to operate differently in the sexes anisogamous parents only female invests in offspring biomass, males invest sperm, most of which go to waste benefits of sexual reproduction
- sex purges deleterious alleles by reversing mullers ratchet
- increases genetic variation - fisher muller hypothesis
- sex and the red queen hypothesis
- benefits is unpredictable environments mullers ratchet irreversible buildup of deleterious alleles
- the ratchet turns when the "best class" (red line) changes - here the "best class" goes from 1 to 2 deleterious alleles
fisher-muller hypothesis acceleration of adaptive evolution due to increased genetic variation and breakdown of linkage disequilibrium - where inheritance can be predicted because it is non-random RQH a species must adapt and evolve not only for reproductive advantage, but also to survive because competitors/ predators are also evolving red queen hypothesis predictions
- oscillations in frequency of asexual lineages when parasites are present
- time lags between the emergence of asexual host defence and pathogen evolution to counter that defence
- correlation between sexual reproduction and parasite load, sexual reproduction increases relative to asexual reproduction when parasitism is high two main benefits from the variability of sex
- increase chance of good fit of offspring with environment
