Natural Selection, Speciation & Conservation

Evolution/Natural Selection

Evolution: Change in allele (Genes) frequency of a population’s gene pool over generations (Time).

Paving the road for Darwin…

Jean Baptiste Lamark (1800s) (Use+Disuse)

• Structures can be modified within one’s life → And can be passed on to offspring (acquired traits)

Charles Darwin (1859) (Traveled around the world → studied animal/plants)

• Ex: Finches on the Galapagos Islands

Adaptive Radiation: Associated with different environmental niches.

• Survival + Reproduction to adaptations to different food sources

Artificial Selection: (Natural Selection)

• But humans choose the traits → Ex: Selective Breeding

• Humans choose the desirable trait of calm dog

• Wolf → Dog over many generations

• Ex:: Teosinte corn

Natural Selection: Has to be heritable

• Reproduction

• Survival

• Beneficial Traits

1. Variation (within) species

   • Mutations (asexually + sexually)

   • Meiosis (Create sperm/egg)

   • Sexual Reproduction/Fertilization

2. OverProduction of offspring (Many offspring die)

3. Competition for resources

   • Ex: Water/Food/Space

4. Differential Survival

   • Successful traits = adaptations

   • Those with adaptations survive in that environment.

   • “Fitness” = Survival + Reproduction

5. Differential Reproduction

   • Those beneficial traits may be passed on to the offspring

   • Those genes/alleles are more prevalent to the population

Ex: Peppered Moth

• Light vs. Dark allele

Ex: Antibiotic resistant bacteria

Measuring Evolution: Through allele frequency

Agents of Evolution

1. Through mutations : only change in the DNA that alters the protein

2. Gene Flow: movement of organisms into/out of an area. Allele pool will change!

3. Sexual selection/non-random mating

4. Genetic Drift: Random placement of alleles (Founder affect)

5. Natural Selection

Gene pool: Total # og genes/alleles in a population

• Ex: A a - Cystic Fibrosis

• Dominant

• Recessive

Large gene pool = Large Biodiversity

Small gene pool = Low Biodiversity

Hardy Weinburg Equilibrium

• Serves as a null experiment

  • Assumptions/no evolution occuring

• No genetic drift

• No gene flows

• No mutation

• Random mating

• No natural selection

P²+2pq+q²=1

p+q=1

p²: AA Homozygous dominant

2pq: Aa Heterosygous

q²: aa Homozygous recessive

Heterozygous “advantage”:

Ex: Sickle cell anemia → carriers = immune to malaria

• The sickle cell gene is more prevalent in Africa (High Malaria)

Speciation

Species: Group of individuals that can mate + produce fertile offspring

New Species: Occurs through isolation + time

• Allopatric: Geographic Isolation (Species Separated physically)

  • Ex: Chimpanzee and Bonobo

  • Chimpanzee: Compete w/ the Gorilla, aggressive, male dominated

  • Bonobo: Don’t live with Gorilla, Calm, female dominated

• Sympatric: Same Location

  • Ex: Behavioral Differences

Pre-Reproductive Barriers: (Pre-Zygote)

• Ecological Isolation

  • Same location/occupy different niches

  • Snake (Water & Land)

• Temporal Isolation (Timing)

  • Same location → behavioral differences

  • Ex: Mate @ different seasons

• Behavioral

  • Courtship (Bird Song)

  • Unique Behaviors

• Mechanical

  • Anatomy does not fit together

• Gametic Isolation

Post Reproduction: (Hybrids)

• Hybrid Viability: hybrids are less likely to live a long/healthy life due to incompatibility

• Hybrid Fertility: Many hybrids are infertile if they have an odd # of chromosomes

  • Ex: 24 + 23 =47

• Hybrid Breakdown: Viable the 1st generation but become less viable each generation

Abrupt speciation in plants:

Polyploidy: Extra sets of chromosomes

Cause: larger fruit/plants force with colchicine: causes chromosomes to fail at separating

• Ex: Allium (onion)

Adaptive Radiation:

• Increase biodiversity

• Species fill certain niches

Selective Pressures:

Stabilizing: Middle phenotype is favored

Disruptive: Both extremes are favored/rare/lead to new species

Rate of Evolution:

• Gradualism (Slower)

• Punctuated (Faster)

Evidence of Natural Selection

Fossil Records: Imprints in sedimentary rocks

• Change over time

• Relative dating: older organisms are @ the bottom

• Radioactive dating: Knowing the age of the rock or fossil = the age of organism

  • C^14 dating

  • K-40 dating (cells), ½ life of 1.26 billion

Artificial selection: Selective Breeding

• Humans select for desirable traits/phenotypes = increase allele frequency

  • Ex: Modern Corn (Natural selection)

Antibiotic Resistance: Bacteria with the resistant (Mutation) trait live (are not killed by antibiotics

• Survive (other die)

• Reproduce…

Homologous traits anatomy: Similar bone structure/anatomy (May have a different use)

• From a common ancestor

• Ex: Pentadactyl Limb (5)

Analogous traits anatomy:

• Not related

• Have the same function

Convergent Evolution

• Evolve to fit a similar niche

• Ex: Dolphin & Shark: Swim

Anatomy Vestigial Structure

• No longer used…the presences

  • Show common ancestry

  • Ex: Whale hip (= used to walk)

Embryology: DNA, Amino Acids, Proteins

• More similar = more related

Biodiversity/Conservation

Types:

• Ecosystem: Habitats, communities, processes (Species interactions)

• Species: # of species (types) + amount of species

• Genetic: amount of diverse alleles (traits)

  • Low diversity: Risk of extinction (cannot adapt to change)

• Ex: FL Panthers, Cheetahs

Species Diversity:

• Richness: total # of species

• Evenness: amount of each species

• Dominance: What species is most abundant

Change in Biodiversity: There is more species now than ever before, due to fossil evidence

• Mass Extinction: There have been 5 major mass extinctions…on the verge of 6?

Extinction: Permanently disappear cannot adapt to there environment

6th? Extinction:

= increased extinction rate (Present day)

• Habitat decline = species decline

  • 50% of the coral reefs are going extinct

  • 1/6 species are at risk of extinction

Keystone species extinction: can cause domino effect

Causes of Biodiversity: habitat destruction

• Fragmentation

  • Deforestation

  • Urbanization

  • Farming

• Monoculture crops (soil nutrients)

• loss of biodiversity

• Ex: Dipterocarp (Tree: Deforestation)

• Ex: Red wolf in NC

Edge Effect: Increase CO_2, runoff, Infection Disease

• Pollution: Air, Water, acid Precipitation (Lead to disease)

• Overhunting

• Invasive Species: Non-native species that is introduced

  • No natural predators

  • Ex: Kudzu vines: Brought to America from Japan grows out of control/on top of other species…out competes the native species

  • Ex: Cane Toad

• Overfishing: Decrease in Biodiversity

  • Problem: It is worldwide

Dilution Hypothesis

Loss of biodiversity

• Reduces genetic diversity = increase risk to disease

• Any introduction of disease can decrease biodiversity

  • Rodents are resilient to disease

Human Population: Lead cause of Biodiversity loss

Monitor Diversity:

• Keystone species:

  • Species that will affect other species in the ecosystem

  • others rely on it

  • A cascade effect on the ecosystem

  • Ex: Beaver → Create Dams + Rivers

Conservation:

1. Prevention

2. Improvement

3. Use natural resources

4. global + economic awareness

In-Situ conservation: “On-Site”

• Recover species

• Ex: Nature reserves/regulations: limit human impact

Ex-Situ conservation: “Off-site”

Ex:

• Captive Breeding

• Seed Banks

• Botanical Gardens

Sustainable Harvesting:

Max Sustainable # of species

(How many animal can be hunted without harming the population)

EDGE of Existence:

Evolutionary distinct + Globally endangered

• Protects organisms on the verge of extinction