Evolutionary Biology

Evolution

• Biological change over time, shaped by species relationships and their environments
• Change in inherited traits of species over time

Rate of Evolution Factors:

• Variation within a species (no two organisms are identical)
• Reproduction method and rate
• Selection favoring the best-suited and adaptable

Evolutionary Change

• Specific, observable changes in an entire population or species

Evolutionary Fitness

• Specific trait improving individual survival and reproductive success

Selective Advantage

• Nature selecting for traits that enhance survival and reproduction

Rate of Change

• Can be rapid or slow

Genetic mutations

• Random changes in DNA contribute to genetic variation
• These create new genes and information and can have immediate/direct or influence inherited traits

Sexual reproduction

• Creates new genetic material combinations

Gene flow

• Movement of genes between populations contributes to genetic variation

Mutations:

• Neutral mutations do not result in selective advantage or disadvantage
• Harmful mutations decrease reproductive success (e.g., sickle cell anemia, Huntington's disease)
• Beneficial mutations increase reproductive success, favored in environments (e.g., longer necks for giraffes or resistance to Huntington's)

Artificial selection

• Directed breeding for specific traits, creating new breeds with desirable qualities

Domestication Example

• Wolves bred into the "ideal" dog

Plant Breeding

• Wild sea cabbage selectively bred into cauliflower, broccoli, kale

Limitations of Artificial Selection:

• Cannot create traits that don't exist in the population; mutations are only a source of information
• Desired traits accompanied by undesirable ones

Impact

• Artificial or natural selection reduces genetic variability, contributing to biodiversity loss

Early Beliefs

• Early views often attributed the way things are to religious or philosophical beliefs

Du Buffon's Contribution

• Comparison of animal anatomical features using the scientific method

Carl Linneaus/Erasmus Darwin

• Proposed all life had the ability to change and originated from a common ancestor

Jean-Baptiste Lamarck's Theory of Evolution:

• First to propose a mechanism for evolution
• Evolutionary change results from use and disuse of structures, and Inheritance of acquired traits
• Use and disuse is when structures an individual used became larger/stronger and not used became weaker
• Inheritance of acquired characteristics is when individuals could pass on characteristics they had acquired during their lives, this is false

Key principles of Evolution

• All species evolve over time
• Species evolve to better adapt to their environment.
• Changes passed from generation to generation

Fossils

• Preserved remains of dead organisms
• Formed when remains are buried and gradually replaced by minerals
• Lack of oxygen prevents decomposition and helps form fossils

Fossilization

• Organisms can be fossilized in tree sap (preserved in amber) or trapped in volcanic ash/ice

Fossil Record

• Many fossils represent unusual organisms no longer living, not most living species
• Fossils are buried deep and found in unexpected places

Georges Cuvier's Key Findings:

• Simple organism fossils found in all depths
• More complex organism fossils are only found in shallower depths

Deeper Fossils

• Fossils at shallower depths resemble living species
• Rock layers contain fossils of species that do not occur in the same layers, indicating extinction

Catastrophism

• Patterns in fossils caused by global catastrophes that wiped out most species
• Does not explain complexity increasing; supports different species groups in each layer

Charles Lyell

• Opposed Cuvier

Uniformitarianism

• Geological changes are slow, gradual, and natural laws that have not changed over time
• Change is not fast or catastrophic, Earth is old and evolutionary change takes a long time

Charles Darwin

• "Father of Evolution," wrote on "The Origin of Species" and came up with the theory of evolution by natural selection

Creationism

• The belief that God created all living things to be unique

Evolution

• Organisms have changed over time, this theory proposes

Darwin's Voyage

• Observed, recorded, and collected rocks, minerals, plants, and animals, with thousands of specimens
• Galapagos Islands off the west coast of South America
• These are 18 islands formed from volcanoes
• Islands feature geographically isolated species with unique characteristics, making migration difficult
• Supported by evidence from fossils, biogeography, anatomy, embryology, biochemical/DNA analysis

Biogeography

• The study of the geographic distribution of organisms, based on living species plus fossils

Galapagos Islands

• An assortment of species on remote islands that were arrived by air or water

Darwin’s Observations & Hypothesis

• Many species found nowhere else with resemblance to mainland species
• Animal were usually fearless/sea lions lie next to humans, birds land on head

Hypothesis

• Species traveled by air or water to islands - evolved into new species different from mainland species

Homologous Features

• Structures in different species (at least 2) that are similar, but could have different functions.
• Pentadactyl limb is a forelimb in mammals with similar bone structure and position, but different uses.
• All species evolved from common ancestor

Modified structures

• Structures modified for environments
• Divergent evolution is when related species adapt and develop different traits to adapting environments

A backbone

• Vertebrate embryos all have one - showing a common ancestor

Analogous Structures

• Display features with similar function but are not similar in design/origin
• Wings of birds and wings of insects

Convergent Evolution

• Unrelated species evolve similar traits because they adapt to similar pressures

Vestigial Features

• Features no longer serving function
• "Evolutionary baggage" is useful in ancestor but becomes useless as species evolved

DNA Evidence

• Closely related species have similar homologous genes

Economist Thomas Malthus

• Populations can't grow indefinitely and population is limited by environment
• Competition for survival between species members

Theory of Evolution by Natural Selection

• A non-random process where the environment/nature favors reproductive success for some individuals within a population
• Survival of the fittest describes natural selection.
• Fitness is the ability to survive and reproduce
• Species evolve in response to climate change

Selective Pressure

• Pressure on phenotypes to undergo competition, predation, environmental stresses, mate choice
• Adapation and survival helps organisms survive and reproduce in the current environment

Natural and Artificial Selection

• Both acts on genetic variation and creates selective pressure
• Both lead to traits that help with survivial and reproductive advantage

Types by Selection

• Structural is the physical selection (beak shape, coloration)
• Behavioral is the migration, mating dance, hibernation
• Physiological is the processes within organisms like venom, thermoregulation and water regulation