Biology 182 - Brad Jacobson 720-9BI-O181
Must know everything on the terms list!
Thesis on Ants – Social insects
What is a species? A very wide metaphysical idea. Tree frog lives on the east coast and the frogs that live in Maine are completely different than in Florida. The ones in Maine can mate with the ones in New Hampshire, etc (ie nearby) but the ones in Florida cant mate with the ones in Maine. The one in Maine is considered a different species than the one in Florida, but the one in New Hampshire and and Maine considered same species with hybrid species resulting from the two.
Why can’t species mate? Cannot fertilize is a pre-zygotic isolation. Anything that keeps them from fertilizing an egg. Geographic isolation – They live far apart from each other. Different mating seasons – benefit of having different mating seasons includes availability of resources and energy. Don’t want them mating and creating offspring that cannot procreate. Mating behaviors - attract the different sexes to each other. Mechanics – ie horse sized penis and Chihuahua sized vagina it’s not going to work.
What happens if the egg does get fertilized? Like a horse and donkey create a mule – the mules cannot reproduce because there is a chromosomal breakdown when trying to create the haploid cell. Hybryd sterility.
Go back to the frogs… The ones in the middle can be classified as hybrids, but they are genetically viable and can mate with each other and create viable offspring.
Ants. Red and black ants, their ancestral lineage used environmental cues to make their workers. At some point they hybridized creating offspring with genetics from both. Example of two species that hybridized and became their own lineage and out competed the parental species and replaced them.
In lab going to look at how we order species and group things together based on similarities. Two types of categorizing one based on Taxonomy/morphology based on physical characteristics (stuff you can see)(form and function) or can be categorized by Phylogeny which is based on shared evolutionary history. Phylogeny takes into account genetics.
Haploid cells are a result of the process of meiosis, a type of cell division in which diploid cells divide to give rise to haploid germ cells. A haploid cell will merge with another haploid cell at fertilization.
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Species Definition Mayr's Species Definition – Can reproduce and offspring are viable and have the same level of fitness. This definition excludes one group -The biological species definition does not work for asexually reproducing organisms. For example bacteria – reproduce via mitosis. (TEST QUESTION) Paradox in Meiosis – Why if a perfect genotype does it choose to split up it’s genes rather than make a perfect replication. Ex. Aquatic Rotifer – can choose whether it wants to reproduce sexually or asexually depending upon its environment. Fitness – relative measure of survivability and reproduction of one genotype relative to other genotypes in the same population. Morphological or Typological Species Definition – Can define a species by shared, visible, objective characteristics. Use physical traits to define what it means to be a member of that species. Phylogenetic (Cladistic)/Evolutionary Species Definition – Differs from taxonomy which uses physical characteristics where Phylogeny looks at a species over time. What is their shared history? Use DNA to make comparisons.
Gene Flow – Genes that provide a greater level of fitness that allow greater survivability and the gene presentation will spread Barriers to gene flow, Geographic, Prezygotic What is the relationship between gene flow and speciation? The squirrels that lived near the grand canyon were one species, but were eventually separated by a physical barrier and could no longer exchange genes. Eventually differences developed between the two sets of squirrels creating two new species that were unable to