1. How do organisms balance energy expended with energy gained?

2. Outline:
Acquisition of energy and nutrients
Respiration
Homeostasis
Water balance
Biological rhythms

3. Energy and nutrient acquisition
Mouthparts give insight to diet
Mosquito sucking
Grasshoper chewing leaves
Strong conical bill of a seed-eating bird
Beak of Hawk - ripping and tearing
Grazers / browsers - eat plants, grinding molars of a deer
Canine and shearing teeth of a carnivorous mamaal (coyote)

4. Detritivores
For plants fairly simple in terms of getting energy: need sunlight, nutrients, water
For animals: they can choose from hundreds of thousands of different types of potential food items…
Ultimate source: plants
Animals: high in fat and proteins
Classification based on the way animals feed: don’t forget omnivores!!!

5. Herbivores

6. Types of herbivores Grazers - leaf tissue Browsers - woody tissue
Granivores - seeds
Frugivores - fruit
Nectivores - nectar
Phloem feeders - sap
High cellulose (fiber), low protein
Animals can’t digest cellulose (no cellulase enzymes)
Need symbiotic bacteria, protozoa

7. Ruminants (e.g. cows, sheep, deer)
Ruminants - complex four component stomachs
Omasum - true stomach
Rumen/reticulum - fermentation and regurgitation
Retain what you need - if food intake is watery, get rid of water

8. Non-ruminants (e.g. rabbits, horses)
Herbirvores eat plants that are high in cellulose, hard to digest, need microorganisms (gut symbiots) to break down cellulose - anearobic,
Fermentation - converst sugars to inorganic acids and alcohols in the absence of oxygen (less efficient than aerobic respiration)
Long intestine and well-developed caecum (where fermentation takes place)

9. Coprophagy = ingestion of feces
E.g. Lagomorphs (rabbits, hares & pikas)
E.g. Detritivores

10. Figure 7.2c
Simple stomach, gizzard
Herbivourus birds have a three part tract
Crop- for storage of food
Gizzard - functions as a powerful grinding organ, plus birds swallow smallpebbles and gravel to assist in grinding action

11. N and food quality
For herbivores, food quality increases with increasing N content
In animals, C:N ~ 10:1
In plants, C:N ~ 40:1  herbivores limited by N availability
Highest in growing stems, leaves, buds
Decreases as plant ages
Herbivores usually born in spring

12. Carnivores

13. Composition of food similar to own tissues --> simple stomach
--> small caecum
Need to get enough food
Simpler stomach
Flesh of herbivoe and carnivore is similar, carnivores encounter no problem in digestion and assimilation of nutrients
Major problme I sobtaining a sufficient quantity of food

14. Omnivores Feed on > 1 trophic level, e.g. plants and herbivores
Diet varies with season, life cycle

15. Diet breadth Generalists: “polyphagous” – eat >1 prey species
Specialists: “monophagous” – eat one prey species – or eat specific part of prey
E.g. seed-eating birds
Specialists are usually
Short-lived (active only when food is available)
Highly adapted to a specific food type (can’t use any other)

16. RESPIRATION
C6H12O6 + 6O2  6CO2 + 6H2O + ATP

17. Figure 7.5a
Trachael system and spiracles of an insect: air enters the trachael tubes thrrough spiracles (openings on wall)
Tracheal tubes carry oxygen directly to the body cells
For minute terrestrial organisms, oxygen diffuses into the body

18. Figure 7.5b
Most larger animals have lungs
Birds have accessory air sacs
2 cycle gas exchange, highly efficient, system evolved for bird lifestyle..

19. Figure 7.5c
Highly efficient system of getting oxygen from water
Gill fillaments have flattened plates (lamellae). Blood flows through capillaries within the lamellae picks up oxygen from water through countercurrent excharnge

20. Figure 7.5e
Counter flow, blood enters gill low in oxygen, picks up oxygen

21. HOMEOSTASIS

22. THERMOREGULATION Figure 7.6 Thermoregulation
Homeasotasis depends on negative feedback
Thyroid controls how quickly the body burns energy

23. TEMPERATURE REGULATION
TYPE OF HEAT PRODUCTION:
Endothermy: - heat from within
Ectothermy: - heat from without
Heterothermy - employ endo and ectothermy in different situations
TEMPERATURE VARIATION:
Homeothermy - constant temperature
Poikilothermy - variable temperature
Figure 7.7
Heat exchange..between organisms and environment:
Fat: good insulator
Muscle/fat influences the organisms thermal conductivity (ability to exchange heat with the surrounding environment)
Must maintain core body temp. 1. Changes to metabolic rate 2. Heat exchange
Aquatic animals live in a more stable energy environment, but they have a lower tolerance for temperature changes.
Temperature regulation:
Homeotherms - invariable temp
Poikilothermy - variable temp
Endotherms: heat from within
Ectotherms - derive their heat from environment
Heterotherms - mixing endo and ecto

24. TEMPERATURE REGULATION poikilotherms
Figure 7.8
Rising temperature increase the rate of enzymatic acticity, which controls metabolism and respiration
For every 10 rise in temp, the rate of metabolism in poikiltherms approximetaly doubles

25. TEMPERATURE REGULATION poikilotherms
Figure 7.9
The range of body temperatures at which poikilotherms carry out their daily activities is the operative temperature range
Lizaards and snakes vary body temp by no more than 4 to 5
Amphibians by 10
Operative temperature range

26. TEMPERATURE REGULATION poikilotherms
Acclimatization
Seasonal adjustment to temperature (acclimatization) of bullhead catfish
Fish are highly sensitive to rapid shifts in temperature

27. TEMPERATURE REGULATION poikilotherms
Lizards and snakes: body temperature varies only 4-5oC/day

28. TEMPERATURE REGULATION homeotherms
Rate of respiration for homeothermic animals is proportional to their body mass
Thermoneutral zone is a range of environmental temperatures within which the metabolic rates are minimal

29. Endothermy – ectothermy tradeoffs
Endothermy and ectothermy involve trade-offs
Endothermy allows animals to remain active regardless of environmental temperatures (the cost for this is that the majority of caloric intake goes towards respiration and not growth
Ectotherms slowed by environmental temperature but put more food intake to biomass (can curtail metabolic activity in times of food and water shortage and temperature extremes
One of the most important feature of animal that allows for heat regulation is size.
Animals looses heat all across surface area but the entire body mass needs to be heated.
This imposes constraint in distribution of ectotherms: large ones can only survive in the tropics!!
Constraint for hometherms is opposite: the smaller organismscan’t produce enough heat (it is lost too quickly)

30. Endothermy tradeoff Figure 7.14
Small homeotherms have a higher mass-specific metabolic rate and consume more food energy per unit of body weight than large ones..
Small shrews eat each much as they weigh every day
Small homeotherms undergo daily torpor

31. Conserving energy – ectothermy for juveniles
Because of their small size (high surface: volume ratio) and their need to invest energy in growth, juvenile birds and mammals are often ectothermic, obtaining heat from their parents.

32. Conserving energy – hibernation
Torpor - dropping of body temperature to apprixmately ambient temperature for a part of the day
Hibernation - dropping of body temperature (below 10), heart rate, respiration, total metabolism fall, acidosis (high levels of CO2, lowers threshold for shivering and reduces metabolic rate
Bears-recycle urea through bloodstream, metabolism near normal
Bears are not true hibernators; their body temperature drops only a few degrees, and they are relatively easily awakened

33. Conserving energy – countercurrent heat exchange
without
Figure 7.15a Unique physiological means for thermal balance
camel stores body heat and releases it at night
-supercooling, resistance to freezing - increase glycerol in body fluids, which protects against freezing damage
To conserve heat in a cold environment and to cool vital parts of the body under heat stress, a number of animals have evolved countercurrent heat exchange
Artery coming from the lungs
Vein going toward the lungs
with

34. Releasing energy – countercurrent heat exchange
RETE
Oryx (antelope), cools brain by 2 to 3 degrees

35. Adaptations to aridity and heat
Figure 7.18 water balance
If not enough water, animals migrate, go belowground, adaptations to withstand drought, concentratted faeces, dehydrate

36. Water balance in aquatic environments
Freshwater organisms: hyperosmotic (water wants to move inside of organism
Marine organisms: hypoosmotic (water wants to move outside of organism
Figure 7.19
Freshwater: loose water copious amounts of watery urine
Marine: match salt concentrations to outside,

37. Controls on activity Figure 7.20
Critical daylength triggers seasonal responses
Flying squirrel

38. Figure 7.21
Signal for these responses is critical daylength
When the duration of light (or dark) reaches a certain proprtion of the 24-hour day, in inhibits or promotes a photoperiodic response
Day-neutral - no controlled by daylength
Short-day - stimulated by daylength shorter than critical daylength
Longday- stimulated by daylength longer than critical daylength
Diapause (stage of arrested growth over winter in insects of temeprate regions) is controlled by photoperiod

39. Human diurnal cycle
Daily and seasonal light and dark cycles influence animal activity
Animals have internal biological clocks - influence hormones that play a role in sleep and wakefullness, metabolic rate and body temperature
Main physiological functions of animals governed by a 24-hour clock, known as circadian rhythm, light and dark sensitivity drives it
Where is the clock?
Operation involves special hormone, melatonin (more of it produced at night)
Why? Provide organism with a time-dependent mechanism, enables the organism to prepare for periodic changes in the environment ahead of time
It lets insects, reptiles, birds orient themselves by the position of the sun

40. A simple life history
Life history = schedule of birth, growth, reproduction & death

41. Asexual or sexual Different forms of sexual reproduction
Types of reproduction
Asexual or sexual
Different forms of sexual reproduction

42. Figure 8.2a
Separate male and female individuals

43. Figure 8.2b
hermaphroditic

44. Simultaneous hermaphrodites
Figure 8.3
Common in invertebrates: earthworm: simultaneous hermaphrodite both male and female organ
Sequential hermaphrodites: mollusks/echinoderms, females first than males

45. Sex change
Figure 8.4
Parrot fishes inhabiting coral reefs exhibit sex change

46. Mating system Strength of bond: Types of bonds:
Monogamy (strong) - Promiscuity (no bond)
Types of bonds:
Monogamy (one-to-one)
Polygamy (one-to-many)
Polygyny (one male, many females)
Polyandry (one female, many males)
Monomgamy - most prevaltn amng birds, rare among mammals (foxes, weasels, beaver, muskrat)
In polygamy, the individual having multiple mates is generally not involved in caring for the young.

47. POLYANDRY: African Jacana
Figure 8.6
Example of polyandry are rare but: male African Jacana, the male incubates the young while the female seeks additional mmates.

48. Intrasexual selection
male-to-male or female-to-female competition for the opportunity to mate
How do animals choose mates?
One form of selection is based on physical competition
This leads to exagertaed secondary sexual characteristics, such as large size, aggressiveness, organs of threat

49. Intersexual selection differential attractiveness of individuals
Involves the differential attractiveness of individuals of one sex to another: results in bright or elaborate plummage used in sexual displays

50. Reproduction is costly
Figure 8.9
Organisms budget time and energy to reproduction
The time and energy allocated to reproduction make up an organisms reproductive effort
Negtive relation between cones and tree ring width
Life histories represent trade-offs; compromises between competing objectives
Herbacis plants invest 15 to 20 % of ANP to reproduction
Female salamander spend almost 50% of its annual energy budget on repro.
Cost of care and nourishment
Fitness is determined by the # of offspring that survive and reproduce

51. Timing of reproduction
Semelparity - reproduce once and die
Iteroparous - reproduce throughout lifetime

52. European grasshopper, Chorthippus brunneus
An iteroparous summer annual

53. Pigweed, Chenopodium album
A semelparous summer annual

54. Semelparous perennials
Coho salmon: a long-lived semelparous animal
Dies after spawning (2-5 yrs)
Overlapping generations

55. Bamboo Semelparous perennials Both genets and ramets are semelparous.
Genets can live for 200 years before the simultaneous flowering of all ramets.

56. Parental investment Figure 8.10
Parental investment depends on the # and size of young
If the parent produces a large # of young, it can afford only minimal investment in each one
EG. Plants store little food energy in seeds
Some organisms spend less energy during incubation
Altricial - born are born in helpless condition- require considerable parental care
Precocial - longer incubation, able to move about and forage for themselves

57. Fecundity Figure 8.11a Fecundity depends on age and size
Big-handed crap off of New Zealand
Similar relati0onship for some endothermic animals - lifetime reproductive success of European red squirrel

58. Fecundity
Figure 8.11b

59. Figure 8.13
Reproductive effort varies with latitude? Why?
-Foraging time is longer in temperate regions
-More climate extremes in temperatr regions so species produce more offspring to offset losses
-winter food supply: if food supply low, more individuals die more available for larger clutch sizes

60. Reproductive tradeoffs
Interpreting trade-offs
One trade-off is the # and size of offspring
Based on this graph alone what would we conclude?

61. Reproductive tradeoffs

62. Reproductive tradeoffs
Multiply probability to # of seeds per plant

63. Reproductive tradeoffs

64. r and K strategists Robert MAcArthur and EO Wilson developed it
Useful to compare similar species

65. For next lecture:
Please read Chapter 9, 10, 11, 12