BIOL 1108 Exam 1

biology

-study of LIFE

-living organisms

have cells and possess their own replication, transcription, and translation machinery, engage in metabolism, are capable of growth, and typically maintain a relatively stable internal environment

hypothesis

proposed explanation that is testable and falsifiable

prediction

often if/then statements generated for experimental tests of hypothesis

scientific theory

widely accepted explanation supported by facts and experiments

T/F: theory and hypothesis can be used interchangeably

false

evolution definition

-simple: change over time
-textbook: descent with modification
-precise: change over time in the genetic composition of a population

natural selection

differential success in survival and reproduction caused by environmental factors

Natural selection: Darwins 4 observations

-Observation #1: Members of a population often vary greatly in their traits

-Observation #2: Many of these traits are inherited from parents to offspring

-Observation #3: Species are capable of producing more offspring than their environment can support.

-Observation #4: Lack of resources will prevent many of these offspring from surviving.

natural selection: darwins 2 inferences

-Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals

-Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations

evidence for evolution by natural selection

adaptation

-a GENETICALLY INHERITED characteristic that enhances an organisms' ability to survive and reproduce

-learned behavior passed down generation to generation is not an adaptation

biological fitness

contribution an organism makes to the gene pool of the next generation, relative to the contribution of others

artificial selection example

wild mustard: selective breeding by humans gave rise to kale, brussels sprouts, broccoli, cabbage, etc

natural selection example on observable timescale

-covid-19
-flu
-antibiotic resistance
-soapberry bugs

taxonomy

process of naming and classifying organisms

phylogeny

evolutionary history of a species or group of species, usually presented as a tree

systematics

discipline of determining phylogenetic relationships

taxonomic hierarchy order

-Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

monophyletic

ALL descendants came from one common ancestor (clade)

paraphyletic

consists of an ancestral species and some, but not all, of its descendants

polyphyletic

invalid group that does not include its common ancestor

homology

similarity resulting from common ancestry (two lineages with inherited similarity)

convergent evolution

independent evolution of similar structures, functions or behaviors in unrelated groups (usually due to environmental pressures and natural selection that lead to production of similar adaptations from diff evolutionary lineages)

horizontal gene transfer

genes are transferred from one genome to the genome of another unrelated organism and perhaps through fusions of different organisms

allele

different copies of the same gene or place in the genome

genotype

An organism's genetic makeup, or allele combinations.

phenotype

An organism's physical appearance, or visible traits.

mutation

change in a DNA sequence that affects genetic information; can occur through

directional selection

favors individuals at one end of phenotypic range

stabilizing selection

favors intermediate variants and acts against extreme phenotypes

disruptive selection

favors individuals at both extremes of phenotypic range

intrasexual selection

direct competition among individuals of one sex for mates of opposite sex (individuals of SAME sex compete)

intersexual selection

individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex

two different types of sexual selection

intrasexual and intersexual

why can't natural selection lead to a perfectly adapted species?

1. selection only acts on existing variation; it cannot magically create new, improved alleles

2. adaptations are often compromises

3. bad recessive genes aren't selected against in heterozygotes

4. a lot of evolution is pure luck/chance (drift, mutations)

5. environments are always changing

genetic drift

random change in allele frequencies that occurs in small populations

reproductive isolation

biological factors (barriers) that impede two species from producing viable, fertile offspring

prezygotic barriers

impede different species from attempting to mate, prevent the successful completion of mating, and/or hinder fertilization if mating is successful

-types: habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

habitat isolation

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers

temporal isolation

Species that breed at different times of the day, different seasons, or different years cannot mix their gametes

behavioral isolation

courtship rituals, specific vocalizations, and other behaviors unique to a species are effective barriers

mechanical isolation

Morphological differences can prevent successful mating

gametic isolation

sperm of one species may not be able to fertilize eggs of another species

postzygotic barriers

prevent hybrid zygote from developing into a viable, fertile adult

-types: reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

reduced hybrid viability

genes of the different parent species may interact and impair the hybrid's development

reduced hybrid fertility

Even if hybrids are vigorous, they may be sterile

hybrid breakdown

first generation hybrids are fertile, second generation offspring and onward are feeble, sterile, or inviable

major species concepts

-biological

-morphological

-phylogenetic

biological species concept

-species are groups of interbreeding natural populations that are reproductively isolated from other such groups

-cannot be applied to asexual organisms, fossils, or organisms about which little is known regarding their reproduction (like dinosaurs)

morphological species concept

defines a species by structural features; applies to sexual and asexual species but relies on subjective criteria

phylogenetic species concept

defines a species using phylogenetic; usually DNA based

-applies to sexual and asexual species; gaining favor, but you need DNA or a big dataset of characteristics comparable across species

allopatric speciation

-gene flow interrupted when a population is divided into geographically isolated subpopulations

-after separation, they may evolve independently through mutation, natural selection, and genetic drift

-more geographic barriers=more

sympatric speciation

takes place in geographically overlapping populations

-caused by polyploidy, autopolyploid, or allopolyploid, or from sexual selection or a single mutation

polyploidy

presence of extra sets of chromosomes due to accidents during cell division (common in plants, usually lethal in animals)

autopolyploid

individual with more than two chromosome sets, derived from one species

allopolyploid

species with multiple sets of chromosomes derived from two or more different species through hybridization events

hybridization

Breeding technique that involves crossing dissimilar individuals to bring together the best traits of both organisms

what kinds of rocks contain fossils?

sedimentary

radiometric dating

-the process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products

carbon dating

used to tell the age of organic materials up to 75,000 years old

K-Ar dating

-most commonly used for mineralized fossils (K is solid, Ar is gas and is free to defuse if exposed to air, but once rock forms and solidifies Ar gas can't escape and concentration in rock can be measured), accurate in volcanic rocks

geologic record is divided into

Eon >Era > Period > Epoch

3 eons

Archaean, Proterozoic, Phanerozoic

3 major eras of Phanerozoic eon

paleozoic, mesozoic, and cenozoic

how are the boundaries drawn between geological units?

from major events in the fossil record like extinction events or sudden appearances of new lineages (like cambrian explosion)

3 most important dates

-4.6 BYA- origin of earth

-3.5 BYA- first fossil evidence of cellular organisms

-200,000 YA- first appearance of homo sapiens in fossil record