BIOL 2390 - Topic 7 (part 4)

Life history characteristics

They are evolved adaptations to environmental conditions, which have been shaped by natural selection

Life history characteristics in variable, short-lived environments with high disturbance

They have high reproductive effort, such that they favor reproduction and higher dispersal, because they may not be alive for very long

Dispersal

The ability to move from one location to another

Variable, short-lived environments

Environments with high unpredictability, as a result of natural or human events that leads to disasters, such as…

1.) Flooding

2.) Forest fires

3.) Highways

Life history characteristics in stable, long-lived environments with low disturbance

They have lower reproductive effort, such that they favor slower growth, delayed reproduction, and competitive traits, since they are more sure about being alive for longer

Stable, long-lived environments

1.) Tropical rainforests

2.) Coral reefs

Species adapted to stable vs. variable environments will differ in…

They will differ in life history traits, as they have been specialized by natural selection to survive in the environment they live in

Species adapted to stable vs. variable environments differing in life history traits

1.) Size

2.) Number of offspring

3.) Age of first reproduction

4.) Number of reproductions over a lifetime

r and K strategies

Refers to components of the logistic population growth model, which are shaped by different environments

K in the logistic population growth model

Referred to as the carrying capacity, which is the max number of individuals that an environment can carry

K-type species

They are near the carrying capacity, usually living in a stable environment

r in the logistic population growth model

Refers to the speed at which a population grows

r-type species

They usually live in short-lived environments

r-strategists characteristics

1.) Short-lived with high reproductive rates

2.) Rapid development, with small body size

3.) Produce many offspring, with low survival and minimal parental care

4.) Exploit unstable, temporary habitats

r-strategists in their habitats

1.) They use resources quickly, as they are poorly adapted to stress

2.) Well-adapted for dispersal and colonization in disturbed areas

3.) Have quick maturation and early reproductions

r-strategists examples

1.) Weedy plants

2.) Rodents

3.) Insects

4.) Frogs

5.) Bacteria

K-strategists characteristics

1.) Long-lived, with low reproductive rates with populations near the carrying capacity

2.) Have slow growth, with large body size

3.) Produce few offspring, but provide parental care

4.) Exploit stable, long lasting habitats

K-strategists in their habitats

1.) They are efficient resource users, as they cope well with biotic and abiotic stresses

2.) But they are poor colonizers with slow, restricted dispersal

3.) They also have delayed, but repeated reproductions (i.e. wait for maturity and sufficient resources)

K-strategists examples

1.) Wolves

2.) Elephants

3.) Humans

4.) Birds

5.) Large trees

Can we compare mammals with mammals?

Yes

Can we compare mammals with insects?

No