Biology Chapter 22: Evolution Theories

Chapter 22: Lamarck's Hypothesis of Evolution

Lamarck (1744-1829) proposed two principles for evolution:
- Use and disuse: body parts used extensively become larger and stronger; unused parts deteriorate.
- Inheritance of acquired characteristics: modifications acquired in one's lifetime can be passed to offspring.
This mechanism is not supported by experimental evidence.

Natural Selection

Darwin's main ideas:
- Descent with modification: New species originate from ancestral forms.
- Natural selection: a process where individuals with certain inherited traits tend to survive and reproduce at higher rates than others, due to those traits.

Darwin's Observations and Inferences

Examples of natural selection:
- Dead-leaf moth (Oxytenis modesta) in Peru
- Buff-end moth (Phalera bucephala) in Scotland
Observation #1: Members of a population often vary in their inherited traits.
Observation #2: All species can produce more offspring than the environment can support, and many of these offspring fail to survive and reproduce.
Inference #1: Individuals with inherited traits that increase survival and reproduction in an environment tend to produce more offspring than other individuals.
Inference #2: The unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations.

Chapter 23: Hardy-Weinberg Equilibrium

Hardy-Weinberg Equilibrium - describes the constant frequency of alleles in a gene pool.
- If p and q represent the relative frequencies of the only two possible alleles in a population at a particular locus.
- p² + 2pq + q² = 1
  - p² and q²: frequencies of the homozygous genotypes.
  - 2pq: frequency of the heterozygous genotype.
The principles that must be in place for the Hardy-Weinberg Equilibrium to apply:
- The frequency of the PKU gene mutation must be low.
- Mate selection is random with respect to whether or not an individual is a carrier for the PKU allele.
- Natural selection can only act on rare homozygous individuals who do not follow dietary restrictions.
- The population must be large.
- Migration must have no effect- the population must have similar allele frequencies.

Chapter 23: Microevolution/Genetic Drift/Founder Effect/Bottleneck Effect

Microevolution - the change in allele frequencies in a population over generations, is evolution at its smallest scale.
Three mechanisms cause allele frequency change:
- Natural Selection (adaptation to the environment).
- Genetic Drift (chance events alter allele frequencies).
- Gene Flow (transfer of alleles between populations)
Founder Effect - occurs when a few individuals become isolated from a larger population.
Bottleneck Effect - a sudden reduction in population size due to a change in the environment.

Chapter 24: Biological Species Concept and Reproductive Isolation

Biological Species Concept - states that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations.
Prezygotic barriers block fertilization:
- Preventing different species from attempting to mate.
- Preventing successful completion of mating.
- Hindering fertilization if mating is successful.
Postzygotic barriers prevent the formation of viable, fertile hybrids:
- Reduced hybrid viability
- Reduced hybrid fertility
- Hybrid breakdown
Allopatric Speciation - gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations.
Sympatric Speciation - takes place in populations that live in the same geographic area.

Chapter 25: Origin of Life

Protocells may have been fluid-filled vesicles with a lipid bilayer.
Early atmosphere was mostly CO₂ (from volcanic eruptions), before cyanobacteria.
DNA is the genetic material because of its greater stability and storage of genetic information
Fossil dating uses the concept of half-life of radioisotopes.
Serial endosymbiosis - describes the origin of mitochondria and chloroplasts from ancestral prokaryotic cells.

Chapter 26: Phylogenetic Trees and Systematics

Phylogeny - is the evolutionary history of a species or group of related species.
Systematics - is a discipline focused on classifying organisms and determining their evolutionary relationships.
Systematists use fossil, molecular, and genetic data to infer evolutionary relationships.

Chapter 27: Bacteria and Archaea

Gram-positive bacteria stain violet with the dye, have a thick peptidoglycan layer, and are more sensitive to antibiotics.
Gram-negative bacteria stain red with the dye, have a thin peptidoglycan layer, and are less sensitive to antibiotics.
Prokaryotes-
- Photoautotrophs use light energy and CO2 to synthesize organic molecules.
- Chemoautotrophs use energy from chemical reactions and CO2.
- Photoheterotrophs use light to generate energy and carbon from organic molecules.
- Chemoheterotrophs break down organic molecules.

Chapter 28: Protists

Protists are a diverse group of eukaryotic organisms.
The primary groups of protists include chrysophytes, dinoflagellates, euglenoids, slime molds, and protozoa.
Excavata, SAR, Archaeplastida, Unikonta are the four supergroups of eukaryotes and their subgroups.

Chapter 29 & 30: Plants

Land plants share several characteristics with charophycean algae, including walled spores, sporopollenin, and an alternation of generations life cycle.
In alternation of generations, multicellular diploid sporophyte and haploid gametophyte stages take turns in the life cycle.
A cuticle reduces water loss, stomata for gas exchange, and vascular tissue for transport are unique to plants.
In seed plants, the sporophyte is dominant over the gametophyte. Gametophytes produce haploid gametes via mitosis; sporophytes produce haploid spores via meiosis.

Chapter 31: Fungi

Fungi are heterotrophic eukaryotes that absorb nutrients.
Mycelium is composed of hyphae filaments that increase the surface area for nutrient absorption
Septate hyphae are divided into cells by septa while coenocytic hyphae lack septa.
Mycorrhizae are a symbiotic association between fungus and roots that enhance plant nutrient uptake.
Fungi participate in asexual and sexual reproduction, using asexual spores and sexual spores within fruiting bodies.

Chapter 32: Animal diversity I

Animals are multicellular eukaryotes that lack cell walls.
Animals obtain energy by ingesting food.
Animals are more diverse.
The Phylum Mollusca- there are THREE main parts to the body of most molluscs (visceral mass, mantle, and foot), and there are FOUR major classes (Gastropoda, Bivalvia, Polyplacophora, Cephalopoda).
Phylum Annelida - the body is composed of repeated units called segments, and they are divided into three clades (Polychaeta, Oligochaeta, Hirudinea).
All three (annelids, molluscs, and arthropods) are coelomates (have a body cavity).

Chapter 33: Animal diversity II - Arthropoda and Chordata

Arthropods have segmented bodies, hard exoskeletons, and jointed appendages.
Insects undergo either complete or incomplete metamorphosis.
Chordates have a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
The major chordate groups include cephalochordates, urochordates, and vertebrates.

Chapter 34: Chordata- Vertebrates

Amphibians, reptiles, birds, and mammals are vertebrate groups.
Reptiles and birds have an amniotic egg, a shelled egg that can be laid on land.
Mammals are characterized by mammary glands that produce milk for their young and they are endotherms.

Chapter 41-45: Body System function and regulation

Homeostasis - maintain internal balance, using constant temperature and stable internal state.
Positive and negative feedback. Understanding of how the body processes nutrients and produces waste.
Digestive system: mouth, esophagus, stomach, intestines, liver, pancreas.
Respiratory system: nose, mouth, larynx, trachea, bronchi, lungs.
Circulatory system: blood, heart, arteries, veins, capillaries.
Immune system: defending the body against pathogens.
Endocrine system: regulate body processes by releasing hormones.
Excretory system: eliminating waste from the body.
Nervous system: relays messages between different body parts (central nervous system, peripheral nervous system).
Osmoconformers do not regulate their solute concentrations; osmoregulators do.