Chapter 2 Flashcards
Evolution theory
Process by which changes occur over successive generations
Darwins “descent with modification” says
“Living organism are constantly evolving, due into particular to the phenomenon of natural selection. Wishing one species, the individuals that are best adapted to their environment reproduce in greater number than other”
Fundamental Principles of evolution
- Variation within systems exist, in terms of genetic differences and morphological diversity (species change over time and space)
- Species can be selected for in the creation of new variation (natural selection works on existing variations)
- All species reproduce under food availability and suitable habitat
- Species success is dependent on optimum conditions
Basic principles of natural selection
- Ability to vary - does not introduce variation, works with existing variations
- Reproduce in excess - increases opportunity for genetic variation that offers survival advantage
- Changing environments - current modifications may no longer be an advantage
What is a theory
A carefully thought-out explanation for observations of the natural world that has been constructed using the scientific method, and which brings together many facts and hypotheses
Cambrian explosion
Paleozoic era, ~540 M years ago, ancestors of today’s animals appeared, big boom of new plant and animal species, contradicted evolution up until that point
Triassic period
Mesozoic era, ~250 M years ago, mammals appeared
Jurassic period
Mesozoic era, ~200 M years ago, birds appeared
Tertiary period
Cenozoic era, ~ 65 M years ago, Genus Homo appeared, mammals and birds thrive, land bridges appear
What does Cenozoic stand for
New life, age of mammals
Paleocene epic
Warm and humid
Eocene epic
Rapid global warming, flora diversification and dense forests
Ogliocene Epic
Temperatures declined, drier and more seasonal conditions, dry woodlands, and wooded grasslands, ice sheets
Holocene epoch
“Entirely new” 11,700 years ago marks significant plant and animal domestication event
Genus Bos
Can be traced to 2 M yeas ago, most profound changes associated with domestication
What process takes longer evolution or domestication?
Evolution
Eohippus (dawn horse)
Emerged during the Eocene epoch (global warming, marshy), small, fox like, 4 toes in the front, 3 toes in the back
Horse evolution
Old: small, many toes, lightweight, don’t travel
New: larger, toes disappear, need to travel for food, consume more food because less rich
Mutations
Variations that occur randomly through normal biological processes
Genetic drift
Acts on existing variation and occurs by chance
Migration (gene flow)
Variation that occurs through physical processes of movement
How does evolution advance
By irregular, wholly unpredictable steps - the occasional occurrence of a peak shift in some locality at some time, followed by spread through a species
Evolution
The process by which diversity is introduced
Domestication
The process by which striking variation within a species arises
What causes genetic variation
Mutations and migration (gene flow)
What acts upon genetic variation
Natural selection and genetic drift
Miocene epic
Stable, mild temperatures
Pleistocene epic
“Current ice age” period of repeated glaciations
Evolution requires both ____ and _____
Environment and Genetics
Environment
- Populations have the potential to increase exponentially
- Resources are limited
Genetics
- Animals within a population differ in many characteristics
- Characteristics that cause these differences are heritable
Outcome
- Not all offspring produced will survive due to the environment and available resources
- Some animals are more likely to survive than others because of their genetic variation and heritable characteristics
Natural selection is due to
A competitive advantage
Artificial selection by humans is due to
Desired traits
Domestication is
A condition whereby humans control the breeding, feeding, and care of animals
Master Gene Theory
Limited number of divergent pathways because it’s controlled by one or few genes
Gradualism
Many genes involved, and multiple paths diverge, making similarities less likely yet phenotypic similarities occur, continual and slow, single or limited number of genes may start process
Successful domestication requires
Breeding animals in captivity, goal-oriented, increased reproductive ability, brings about atrophy of select organ systems, enables animal to achieve greater plasticity/adaptability, facilitated by subjugation to man
Social behaviors that oppose domestication success
Territorial, monogamous, signals mating readiness through color markings, altricial young, high reaction toward human presence, carnivorous, high stress to confinement
Does social cooperation increase or decrease fitness
Increase
Social behaviors that support domestication success
Large social groups with leaders and followers, promiscuous, signals mating readiness through postures, precocial young, low reaction towards human presence, varied diet herbivore or omnivorous, low stress to confinement
What is the most consequential event in human history
The exercise of dominion over plants and animals
Pushes towards domestication
Climate warming, human expansion, resource depression (necessitated)
Pulls towards domestication
Social status, release from labor, innovation (benefits)
Domestication phases
- Animal attraction
- Animal keeping
- Animal breeding
- Intentional selection
