BIOL305 LIFE HISTORIES

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Questions and Answers

What is a characteristic of an annual species?

It completes its life cycle in 12 months or less (correct)

It invests a lesser proportion of resources in reproduction

It has multiple reproductive events in its lifetime

It persists for many growing seasons

What type of life cycle is characterized by one reproductive event followed by death?

Semelparous (correct)

Overlapping iteroparous

Continuous iteroparous

Iteroparous

Which type of organism has discreet, non-overlapping generations?

Annual (correct)

Semelparous

Iteroparous

Perennial

What is a key difference between semelparous and iteroparous species?

The number of reproductive events Signup and view all the answers

Which type of life cycle is characterized by an organism that persists for many growing seasons?

Perennial Signup and view all the answers

What is a characteristic of an iteroparous species?

It has multiple reproductive events in its lifetime Signup and view all the answers

What is a key difference between continuous and overlapping life cycles?

The duration of their life cycle Signup and view all the answers

Which type of life cycle is characterized by an organism that may or may not overwinter as a non-seed or non-egg?

Annual Signup and view all the answers

What is a characteristic of a semelparous individual?

It has only one reproductive event during its lifetime. Signup and view all the answers

What is a key difference between annuals and perennials?

Annuals complete their life cycle in 12 months or less, while perennials persist for many growing seasons. Signup and view all the answers

What is a characteristic of an iteroparous individual?

It has multiple reproductive events during its lifetime. Signup and view all the answers

What is an example of an overlapping semelparous life cycle?

A species that has multiple generations that overlap in time. Signup and view all the answers

What is a characteristic of continuous iteroparous species?

They have a long lifespan with seasonal breeding. Signup and view all the answers

What is a key difference between semelparous and iteroparous individuals?

Semelparous individuals die after one reproductive event, while iteroparous individuals have multiple events. Signup and view all the answers

What is a characteristic of perennial life cycles?

They have a long lifespan with multiple breeding seasons. Signup and view all the answers

What is a key difference between annuals and perennials in terms of energy investment?

Annuals invest more energy in reproduction, while perennials invest less. Signup and view all the answers

What is a characteristic of semelparous organisms?

They have a single reproductive event during their life, then die. Signup and view all the answers

What is the primary difference between annual and perennial life cycles?

The duration of their life cycle. Signup and view all the answers

In terms of energy investment, what is a key difference between semelparous and iteroparous organisms?

Semelparous organisms invest more energy in reproduction, while iteroparous organisms invest less. Signup and view all the answers

What is the result of the trade-offs between life history traits?

Optimization of survival. Signup and view all the answers

What would be the characteristics of a 'Darwinian Demon'?

It would live forever and produce many offspring continuously. Signup and view all the answers

What is the key assumption underlying life history theory?

There are trade-offs among life history components. Signup and view all the answers

What is the result of constraints on life history strategy?

Shaping of life history strategy. Signup and view all the answers

What determines an organism's Darwinian fitness?

The combination of life history traits. Signup and view all the answers

Study Notes

Life Histories

Life histories are the combination of characteristics that define an organism's life cycle
Main types of life cycles include:
- Annuals vs perennials
- Semelparous vs iteroparous

Semelparous vs Iteroparous

Semelparous: individual has one single reproductive event during its life, then dies
Iteroparous: individual may have many reproductive events (during season or life)
Invests large amount of energy in reproduction vs invests lesser proportion of resources in reproduction

Overlapping vs Continuous

Overlapping semelparous: generations overlap, but still die after reproduction
Overlapping iteroparous: multiple reproductive events, but with overlap between generations
Continuous semelparous: continuous reproduction, but still dies after reproduction
Continuous iteroparous: continuous reproduction with multiple events

Annuals vs Perennials

Annuals: complete life cycle in 12 months or less
May or may not overwinter as non-seed/egg
Perennials: persist for many growing seasons
One part of the organism dies/gets absorbed and regrows from the following season

Life History Traits

Measurable characteristics or attributes that affect survival and reproduction
Examples:
- Size at birth
- Growth rate
- Age/size at maturity
- Number and size of offspring
- Age/size-specific reproductive investments
- Age/size-specific mortality schedules
- Lifespan
The combination of traits determines Darwinian fitness

Life History Theory

Key assumption: there are trade-offs among life history components
"Reproduction is costly, and so is growth" – Trade-off
Constraints shape the life history strategy of species
Examples of constraints include:
- Limited resources
- Environmental pressures
- Predation
Optimization of survival and reproduction is favored by selection

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