Bio Test 4 Flashcards
3 evidence for diversity of life:
-MORPHOLOGICAL EVIDENCE
> Homologous structures
> structures among common species because they have common ancestors.
- Fossil records
> Convergent evolution
> they look closely related because they are in similar environments, but they are not. Eg. Turtle and seal arms. Reptile and mammal… Not similar at all.
-EMBRYOLOGY
developmental stages of organisms have similarities
-MOLECULAR EVIDENCE
mtDNA, rRNA, protein sequences
*Problem with embryology and molecular evidence: have to put it in a lab. Takes technology. Morphological - u can just observe.
Natural selection occurs when three conditions are met:
- Individuals within a population vary in their characteristics.
- eg. skin color, height, gender, eye color.
2. The variable traits are inherited (heritable) - skin color….
3. Fitness - certain heritable traits help individuals survive better AND reproduce more.
Biological fitness
genetically pass on ur survival genes for that environment.
nine forces that can bring changes in population
1 mutation 2 gene flow 3 A&B genetic drift 4 non random mating 5 A, B & C Natural selection 6 Artificial Selection 7 co-evolution 8 Evolutionary adaptation 9 Physiological acclimation
changes in population - Mutation
- changes in the DNA
changes in population - gene flow
- species that are distributed to different areas of the world, the environment is different and species look different.
- Eg. Birds or pollen.
- can result in new species forming
changes in population - genetic drift (random shift in allele frequency)
a. The Bottleneck effect:
- Random event, death is involved eg. Earthquake kills random people
b. Founder effect:
- A subset of the population is isolated and does not represent the same allele frequency as the original population.
changes in population - Nonrandom mating:
- Sexual selection
- the visuals u choose in the partner
changes in population – Three Modes of natural selection:
Polygenic genes:
- stabilizing selection - average, not light or dark.
- Directional selection - towards dark, not light.
- Distributive selection - towards light or dark, no average
changes in population – Artificial Selection
- human involvement)
changes in population – Evolutionary adaptation:
Adaptations are consequences of the environmental change; shift in the gene frequency of the population; occurs in the population; permanent condition (unless the species evolves)
changes in population – Physiological acclimation:
-changes are responses to environment; occurs in the individual; typically temporary
Macro evolution
- Evolutionary change above species
Adaptive radiation =
- many species forming in a very short time span. - the absence of competitions
- Mammals when dinosaurs died.
What is a species?
- a group of individuals that can breed (reproduce) and have a viable (survive) & fertile offspring (can reproduce
REPRODUCTIVE BARRIERS (to keep species separate):
- Pre zygotic barriers (5 different) - inhibit mating between species or inhibit fertilization of egg and sperm.
a. Habitat isolation
- ex live on mountain tops, and never come down - ex zones in water level.
b. Temporal isolation
- refers to time
- ex active different times of the day
- breed different seasons of the year
- ex. Some plants flower in fall, and other in the spring.
c. Behavioral isolation
- for species with courtship rituals to attract mates
d. Mechanical Isolation
- for animals or plants
- morphological differences prevent successful mating - if the pollen don’t fit in the pollen hole
- penis don’t fit.
e. Gametic Isolation
- everything fits, but sperm does not fertilize egg
- receptors on egg and sperm need to match
- Ex, chipmunk and rabbit, but very common for plants, and in water when eggs and sperms floating around mixed up
- Post zygotic barriers (2 different)- inhibit the hybrid zygote from developing into a fertile adult.
a. Hybrid inviability
- zygote starts, but does not survive
- embryos development is impaired when genes from different parents are incompatible
- Cant make functional proteins
b. Hybrid sterility
- zygote develops, but will not reproduce (sterile, infertile) - The hybrid does survive
- uneven number of chromosomes
Background extinctions vs. mass extinction
- Occurs evenly over time.
- 6th mass extinction is mainly due to habitat destruction for agriculture.
- population:
a group of individuals of the same species in an area.
- community:
interactions among the different species in an area.
- ecosystem
living (biotic) and non-living (abiotic) interactions in specific areas = grasslands, kelp forest, tundra.