A Brief Introduction to Functional Ecology (Outline) (relating the performance of organisms’ phenotypes to their environments) - Species have a set of optimal conditions and ecological tolerances that may ultimately define their distribution (average, variability, extremes, predictability) - Adaptation to the physical environment (Chap 4,5,…6) e.g., desert plants - Adaptation to varying environments the “Hierarchy of animal responses” The Fundamental versus the Realized Niche - definitions - e.g., Connell’s barnacle study (1961)

Climate or the physical environment does more than just determine the abundance or distribution of species – it also shapes organisms (morphologically, physiologically, behaviorally, etc.), and similar environments shape organisms in similar ways  Convergent Evolution Cactus, Oaxaca, MexicoEuphorb tree, east Africa

Morphologically, Deciduous leaves are broad and thin producing a large surface area for maximum light absorption, but this also leads to high loss of H 2 O.  TRADEOFFS

Instead, desert plants have small leaves and many edges to reduce the total amount of incoming heat and to lose heat at leaf edges via convection

In addition, leaves possess thick, waxy cuticles and dense hair to trap a boundary layer of air which reduces evaporative water loss

Physiologically, different pathways of photosynthesis CB-cycle requires high [CO 2 ] for efficient photosynthesis  open stomata but opened stomata increase water loss Solution: spatial separation of gas exchange and carbon assimilation CAM plants separate the two processes in time

Fixing CO 2 : spatial temporal segregation segregationneither Stomata open: infrequently infrequentlyand at night often H 2 O loss: low very low high Temp. (C) at max Photo Syn efficiency: Examples: corn, millet, desert most woody most grasses succulents plants C4 CAM C3

C3 C4CAM

Developmentally, in response to unpredictable environments desert plants have evolved seed banks and delayed germination Unpredictability % seeds germinating per year

There are additional convergent characteristics of desert plants that have evolved more in response to other organisms (biotic forces) rather than to the physical environment, e.g., the possession of spines or thorns and toxic substances (oxalic acid, alkaloids, tannins) that reduce herbivory.

A Brief Introduction to Functional Ecology (Outline) (relating the performance of organisms’ phenotypes to their environments) - Species have a set of optimal conditions and ecological tolerances that may ultimately define their distribution (average, variability, extremes, predictability) - Adaptation to the physical environment (Chap 4,5,…6) e.g., desert plants - Adaptation to varying environments the “Hierarchy of animal responses” The Fundamental versus the Realized Niche - definitions - e.g., Connell’s barnacle study (1961)

 Hierarchy of responses What do you do in response to a hot environment? Environments are also constantly changing (in space and in time) and that organisms also possess adaptations that help them cope with their changing environment

The cactus wren’s response to heat: Select cool environments – habitat selection #1: Behavioral response

#2: Physiological response

In response to heat (or at least sunlight): tan -  melanin

#2: Physiological response In response to heat (or at least sunlight): tan -  melanin Acclimate:  red-blood cells at high elevations  density of fur in the winter Trees harden before the onset of winter

#2: Physiological response In response to heat (or at least sunlight): tan -  melanin Acclimate:  red-blood cells at high elevations  density of fur in the winter Trees harden before the onset of winter Behavioral and physiological responses are quick, they are reversible, and occur within an individual’s lifetime (often many times).

#3: Developmental response – Tadpoles developing under the risk of predation, i.e., in the presence of a predator, produce a larger mouth and larger tail w/o pred. with pred.

Daphnia in the presence of the Chaoborus midge develops crests and spines

Unlike behavioral and physiological responses, developmental responses are non-reversible within an individual’s lifetime and most often seen in organisms with several generations/year. Every 3 rd generation of Monarch butterflies are migratory Water striders raised in large ponds develop minute wings, those raised in ephemeral ponds develop either minute wings (hatch in spring) or large wings (hatch in summer).

#4: Evolutionary response – when subjected to persistent environments, organisms may adapt to local conditions such that when individuals are grown under identical conditions they retain their differences  Ecotypes or subspecies e.g., Yarrow (Achillae millefolium)

So in conclusion, what can we say about Abiotic factors, especially climate? (1)Abiotic factors influence species’ distribution and abundance But it also – (2) Shapes organisms: morphology, physiology, and behavior

Darwin’s Postulates: (1)There is heritable variation (2)There is a struggle for existence (3)Variation influences the struggle and Natural Selection follows...

(1) There is heritable variation

Heritability in selected human traits: Handedness30% Diastolic blood pressure45% Twinning50% Systolic blood pressure55% Body weight65% Stature and tooth size85% Fertility10-20% IQ60-80%

(2) There is a struggle for existence Resources are limiting There is competition for resources, including mates

(3) Variation influences the struggle dicots monocots vs.. Columbian ground squirrel

min energy constraint time constraint Digestive constraint Optimal diet Dicots consumed Monocots consumed Mixture of monocots and dicots - Monocots limited by handling time - Dicots limited by digestion

Mark Ritchie compare the predicted “optimal” diet and the actual diet for 109 individuals squirrels Dicots consumed Monocots consumed r 2 = 0.94 (a)variation in the ability to forage optimally

Mother’s deviation Offspring’s deviation (b) optimal foraging is a heritable trait Mothers raise offspring Offspring on their own

(c) There is a struggle for existence Relative to optimal foragers, deviators have lower surplus energy intake and....

(c) Variation influences the struggle... as a consequence, deviators have i) lower somatic growth ii) lower survival iii) smaller litter sizes

Mark Ritchie’s study beautifully illustrates Darwin's Postulates in action: Heritable Variation Struggle for Existence Variation influences the Struggle but...falls short of documenting Natural Selection

Evolution by Natural Selection – Guppies on the island of Trinidad Life history traits

Schooling behavior - dilutes individual risk - greater vigilance - group confusion Predator-inspection behavior - method to ascertain the identity and intentions of the assailant low risk low risk (Magurran et al. 1996)

Male coloration and female choice Predation risk (cichlids) Predation risk (prawns) Low risk Start of exp w/predators w/o Months mean # spots mean size (Endler 1980)

Correlations vs. experimental tests Haskin’s 1957 transplant experiment

black = % females schooling 10mm (Magurran et al. 1996) Transplant experiment results:

Summary: 1) “Natural experiment” – Guppy populations that have experienced different regimes of predation risk show different levels of anti-predator behavior 2) Transplanted (1957) high-risk guppies behave like native low-risk guppies (evolution in 34 years or ~100 generation) 3) Changes in color-patterns that function in mate choice were apparent after 13 months!!