Lecture 7

Question 1

a record of events relating to its growth,

development, reproduction, and survival.

Answer 1

life history

Question 2

life history strategy

Is there an optimal strategy?

how quickly to grow, how many offspring, when to reproduce, how often breeding occurs, etc.

Answer 2

timing and division of resources

Question 3

One genotype may
produce different phenotypes under different
environmental conditions.

i.e. pines in California

Answer 3

phenotypic plasticity

Question 4

Phenotypic plasticity may produce a

continuous range of growth rates; or “discrete types” known as

Answer 4

morphs

Question 5

a single genotype
produces several distinct morphs

i.e. toad tadpoles
carnivorous VS omnivorous

bacteriavore morph vs cannibal morph

Answer 5

Polyphenism

Question 6

Organisms have evolved many different

modes of reproduction.

Answer 6

Asexual reproduction: Simple cell
division—all prokaryotes and many
protists.

Some multicellular organisms reproduce
both sexually and asexually (e.g.,
corals).

Question 7

Simple cell
division—all prokaryotes and many
protists.

Answer 7

asexual reproduction

Question 8

Pros and Cons of Asexual VS Sexual Reproduction

Answer 8

Sexually reproducing organisms cannot reproduce as fast

benefit of sexual reproduction:
genetic variation which enables population to survive with a lot of variation in the gene pool (certain individuals may survive disease, drought stress, etc.)

Asexually reproducing organisms have no need to find a mate

Question 9

involve at least
two distinct stages that may have
different body forms and live in
different habitats

Answer 9

Complex life cycles

Question 10

Transition between stages may be
abrupt

Abrupt transition
in form from the larval to the
juvenile stage.

Answer 10

Metamorphosis

Question 11

Reproductive patterns can be categorized

along several continua.

Answer 11

Semelparous species reproduce
only once.

Iteroparous species can reproduce
multiple times.

Question 12

Semelparous species include:

Answer 12

Annual plants

• Agave—vegetative growth can last
up to 25 years. It also produces
clones asexually.

• Giant Pacific octopus—a female
lays a single clutch of eggs and
broods them for 6 months, dying
after they hatch.

Question 13

Iteroparous species include:

Answer 13

Trees such as pines and spruces.

• Most large mammals.

Question 14

_____ and _____ describe
two ends of a continuum of
reproductive patterns.

Answer 14

r-selection and K-selection

r = intrinsic rate of increase. 
K = carrying capacity

Question 15

is the intrinsic rate of increase of a

population.

Answer 15

r

Question 16

is selection for high population
growth rates; in uncrowded
environments, newly disturbed habitats,
etc.

Short life spans, rapid development, early
maturation, low parental investment,
high rates of reproduction.

Answer 16

r-selection

Question 17

is the carrying capacity for a

population.

Answer 17

K

Question 18

n is selection for slower 
growth rates in populations that 
are at or near K; crowded 
conditions, efficient reproduction 
is favored. 

Long-lived, develop slowly, delayed
maturation, invest heavily in each
offspring, and low rates of
reproduction.

Answer 18

K-selection

Question 19

A classification scheme for plant

life histories is based on ____ and _____ (Grime 1977).

Answer 19

stress and disturbance

Question 20

A classification scheme for plant
life histories:

any factor that reduces
vegetative growth.

Answer 20

stress

Question 21

A classification scheme for plant
life histories:

any process that
destroys plant biomass.

Answer 21

distrubance

Question 22

Grime’s Triangular Model

Answer 22

1. low stress, low disturbance
2. low stress, high disturbance
3. high stress, low disturbance
4. high stress, high disturbance (excluded)

Question 23

There are _____ between life history

traits.

Answer 23

trade-offs

Question 24

Trade-Offs:
In species without parental care, 
reproductive investment is 
measured as resources invested 
in \_\_\_\_\_\_\_ (eggs or seeds)

Answer 24

propagules

Question 25

Size of propagules is a trade-off with ______-

Answer 25

the number of propagules produced

Question 26

For an iteroparous organism, trade-offs | between current and future reproduction:

Answer 26

i.e. Atlantic cod increase reproductive output with age. At 80 cm length, a female produces about 2 million eggs per year. At 120 cm, 15 million eggs per year.

Question 27

Organisms face different selection pressures at | different life cycle stages

Answer 27

Different morphologies and behaviors are adaptive at different life cycle stages. Differences in selection pressures over the course of the life cycle are responsible for some of the distinctive patterns of life histories.

Question 28

i.e. Cod fishing

Answer 28

larger fish harvested a lot more; selective pressure on large cod (artificial selective pressure) large population of smaller individuals

Question 29

Life Cycle Evolution

Answer 29

Predation, competition & environment

Question 30

Life Cycle Evolution Parental Investment: many forms

Answer 30

i. e. the kiwi - nutrition and investment into one large egg that occupies the majority of its body i.e. endosperm - the nutrient-rich material that sustains the embryo during germination (e.g., the milk and meat of coconuts).

Question 31

Life Cycle Evolution | Alternative strategy:

Answer 31

movement (dispersal) - can reduce competition among close relatives and allow for colonization of new areas; can allow escape from areas with diseases or high predation.

Question 32

Life Cycle Evolution State of suspended animation or dormancy—organisms can survive unfavorable conditions.

Answer 32

Diapause Many seeds can survive long dormancy periods. Many animals can also enter diapause Amoeboid protists form a hard shell or cyst that allows them to survive dessication. “Sea monkeys” are brine shrimp eggs that can survive out of water for years. Small size is advantageous for diapause because less metabolic energy is needed to stay aliv

Question 33

Life Cycle Evolution: For some organisms, one stage of the life cycle is specialized.

Answer 33

Even in organisms without abrupt shifts between life stages, different sized and aged individuals may have very different ecological roles. A size- or stage-specific ecological role has been called an ontogenetic niche by Werner and Gilliam (1984).