Chapter 4: Evolution Flashcards
Define: Divergent Evolution
increases differences between species as a result of living in [slightly] different environments
Define: Convergent Evolution
decreases differences between [unrelated] species as a result of adapting in similar environments
Define: Mutation
Accidental changes in DNA
Allopatric Speciation
When new species are generated as a result of the same species being separated into different geographical locations
Directional selection
When a trait is driven in one direction(ex. if all snails adapt to have thick shells)
Stabilizing Selection
When a intermediate trait is favoured(ex. all snails adapt to have shells of intermediate thickness)
Disruptive Selection
When traits diverge in two or more directions(ex. some snails have thick shells, some have thin shells)
Sympatric Speciation
When species from populations become reproductively isolated within the same area(ex. species mating at different seasons)
Phylogenetic Trees
Diagrams representing the divergence and relationship between species, and how certain traits have evolved.
What is the average time a species tends to exist on Earth?
1-10 million years
Extirpation
Local extinction
What does it mean for a species to be ENDEMIC to a region?
Endemic species only exist in one region on Earth
What constitutes a mass extinction?
when 50-95% of all species on Earth go extinct within a relatively short amount of time
What mass extinction are we currently living in?
6th- Anthropocene
When did the mass extinction of the dinosaurs occur?
~66 million yrs ago
Ecosystem
communities and the nonliving material and forces they interact with
Biosphere
All the living things on earth and the areas they inhabit
What was the largest mass extinction?
Permian-Triassic ~252 mya
define: cell
The smallest unit of living
matter able to function
independently, made up of organelles
List the hierarchy of matter within organisms from smallest to largest: organ system, organism, molecule, tissue, organelles, atom, organ, macro-molecule
atom, molecule, macro-molecule, organelle, cell, tissue, organ, organ-system, organism
What is the distinction between a community and a population?
Community consists of all the different species living within a region, a population is only one species
What is a species’ NICHE?
the species use of resources and functional role within a community(habitat use, food selection)
Community Ecology
focuses on interactions among species
Population Ecology
investigates the quantitative dynamics of how individuals within a species interact
Ecosystem Ecology
studies living and nonliving components of systems to reveal patterns
Define a SPECIALIST(with regards to species)
A species that has a very specific niche, usually very good at what they do but are vulnerable to change
Define a GENERALIST(with regards to species)
A species with a very broad niche, able to live in many different habitats/environments
What are the benefits/drawbacks of HIGH vs. LOW density population of a species?
High: Easier to find mates, but more competition, vulnerability to predators, and more likely to catch disease
LOW: Harder to find mates, but can leave with more space and resources
What are the three different types of population distribution? Which one is the most common in nature?
Random: individuals are located haphazardly in space with no specific pattern(not common)
Uniform distribution: individuals are evenly spaced.(occurs when individuals hold territories or otherwise compete for space)
Clumped distribution: organisms arrange themselves according to the availability of the resources they need to survive (MOST common)
Define: Crude birth/death rate
Number of births/deaths per 1000 individuals in a given time frame
What are the three fundamental types of survivorship curves?
Type 1: Higher death rates at OLDER ages (eg. Humans)
Type 2: EQUAL death rates at ALL ages (Eg. birds)
Type 3: Higher death rates and YOUNG ages (eg. Frogs)
What four factors determine population growth/decline?
- NATALITY: Births within population
- MORTALITY: Deaths within population
- IMMIGRATION: Arrival of individuals
4: EMIGRATION: Departure of individuals
Exponential Growth
Population grows at a fixed percentage each year
Logistical growth curve
S-shaped curve; rises sharply at first but then begins to level off as the effects of limiting factors(eg. carrying capacity) become stronger
Biotic Potential
The maximum capacity to produce offspring under ideal environmental conditions(ex. fish that can lay many eggs at a time have HIGH biotic potential)
K-selected species
Species that reproduce SLOWLY, long gestation periods(eg. whales)
R-selected species
Species that reproduce QUICKLY, high biotic potential(think R… Rapid)
