Test 3 Flashcards
What is natural selection?
A process where organisms with traits better suited to their environment survive and reproduce more, passing those traits on.
How does evolution relate to natural selection?
Evolution is the change in a population’s genetic makeup over time, driven largely by natural selection.
What are predator-prey dynamics?
The rise and fall of predator and prey populations are interconnected—prey increase leads to predator increase, which then reduces prey.
What are limiting factors in populations?
Factors that restrict population growth like food, space, disease, or weather.
What are density-dependent factors?
Factors like competition, disease, or predation that intensify as population density increases.
What are density-independent factors?
Factors like natural disasters or temperature changes that affect populations regardless of size.
How does mark-recapture estimate population size?
By capturing, marking, and releasing individuals, then recapturing and checking how many are marked to estimate total population size.
Why are population estimates important?
They help assess species conservation status and understand ecological relationships.
What is a keystone species?
A species with a large effect on its ecosystem—its removal causes major changes in community structure.
How do keystone species affect community dynamics?
They often regulate populations of other species, maintaining biodiversity and balance.
What is an ecosystem engineer?
An organism that modifies the physical environment, creating or altering habitats for other species.
How do ecosystem engineers impact ecosystems?
They change resources, structures, or conditions—like beavers creating wetlands.
What is altruism in ecology?
Behavior that benefits another individual at a cost to the actor, often seen in social species.
Why does altruism exist?
Due to kin selection (helping relatives), reciprocal benefit, or social cooperation strategies.
What is mimicry?
One species resembling another to gain protection or other advantages.
What are the two main types of mimicry?
Batesian (harmless mimics harmful) and Müllerian (harmful species resemble each other).
What is mutualism?
A symbiotic relationship where both species benefit (e.g., bees and flowers).
What is intrasexual selection?
Competition among the same sex (usually males) for access to mates.
What is intersexual selection?
One sex (usually females) chooses mates based on traits like songs, colors, or displays.
What are common mating systems?
Monogamy (one partner), polygyny (one male, multiple females), and polyandry (one female, multiple males).
What are the benefits and costs of each mating system?
Monogamy can ensure parental care but limits mating opportunities; polygamy may boost reproduction but can cause competition or neglect.
What is the difference between photosynthesis and chemosynthesis?
Photosynthesis uses sunlight to make energy; chemosynthesis uses chemical energy from inorganic compounds.
How does energy enter a food web?
Through primary producers (plants or bacteria) that convert energy into forms usable by other organisms.
What are trophic levels?
Steps in a food chain—producers, primary consumers (herbivores), secondary consumers, etc.
