Presentation is loading. Please wait.

Presentation is loading. Please wait.

Predation and Parasitism The potential impact of predation is not questioned In fact, it may be one of the most studied aspects of population/community.

Similar presentations

Presentation on theme: "Predation and Parasitism The potential impact of predation is not questioned In fact, it may be one of the most studied aspects of population/community."— Presentation transcript:

1 Predation and Parasitism The potential impact of predation is not questioned In fact, it may be one of the most studied aspects of population/community ecology

2 Predation and Parasitism Evolutionary, this is a classic ‘arms race’ where both sides are showing strong selection to get more efficient (although predator trying to end this relationship!)

3 Predation and Parasitism Long-term escalations have resulted in many complex adaptations Consider socialized hunting

4 Predation and Parasitism Some marvelous adaptations: the tongue

5 Predation and Parasitism Fangs, webs, angler fish

6 Predation and Parasitism Prey have also responded well with many unique adaptations

7 Predation and Parasitism Camouflage is an easy and effective deterent

8 Predation and Parasitism Many prey work to avoid predators through early detection

9 Predation and Parasitism Tight flocking (fig 15.1) Prey in response to Peregrines How do peregrines respond?

10 Predation and Parasitism Predator-prey oscillations (fig 15.2)

11 Predation and Parasitism However, these are rather simplistic approaches to the L-V population equations There are two separate ways in which predators respond to changes in prey density First, individual predators capture and eat more prey per unit time as prey density increases until full (until numbers don’t matter)…(functional response)

12 Predation and Parasitism Three types of functional response. Type I is a very linear response, 2 also responds quickly. Type 3, increases in prey density are not immediately beneficial to predator

13 Predation and Parasitism Second, prey density increases and raises the predator’s population size and they subsequently eat more prey (numerical response) Clearly the relationship between predator and prey is complex and not easily quantifiable

14 Predation and Parasitism A simple graphical model of the prey-predator interaction was developed by Rosenzweig and MacArthur (1963) Maximum prey density (K) exists, as well as minimum density (allele effect) and various levels of prey density will support various levels of predator densities

15 Predation and Parasitism Hypothetical relationship between prey and predator Exact shape not important, but concept of increasing/ decreasing areas is important

16 Predation and Parasitism


18 Relative magnitudes of the changes in the population densities of prey and predator determine another important property of this model: whether equilibrium exists or not Using the vectors, we see 3 possible outcomes: spiral inward, oscillate, or spiral outward (fig 15.8)

19 Predation and Parasitism b

20 Prudent predation and optimal yield An ‘ideal’ predator would crop its prey as to maximize the prey’s turnover rate and therefore the predator’s yield Human’s have this ability, although do a relatively poor job

21 Predation and Parasitism However, do predators take the demographic groups that allow for maximal yield? What about among competing species for a common food source?

22 Predation and Parasitism However, we do see some prudent predation occurring, what else may be occurring? What about looking at it from the prey’s perspective; which individuals have the highest potential reproductive value

23 Predation and Parasitism Selected Experiments and Observations There have been a number of lab experiments and some field experiments (can you think why these may be difficult?) Several microcosm studies have been conducted In ‘simple’ systems, predators usually overhunt

24 Predation and Parasitism

25 Utida (1957) used two species of wasps and a beetle to look at competitors in a predatory- prey relationship Population varied, competitors fluctuated out of phase with one another

26 Predation and Parasitism Evolutionary Consequences: prey escape Generalized predators vs. specialists and their impact on prey escape tactics There may be an advantage to being hunted by more than one species… aspect diversity

27 Predation and Parasitism Cryptic coloration needs to be partnered with behavioral attributes

28 Predation and Parasitism Almost all diurnal species have countershading

29 Predation and Parasitism Many insects mimic plant parts

30 Predation and Parasitism Other examples

31 Predation and Parasitism Classic example

32 Predation and Parasitism Disruptive coloration is another great tool

33 Predation and Parasitism Flash coloration

34 Predation and Parasitism Disruptive burst

35 Predation and Parasitism Alarm signals: remember, this is NOT altruistic!

36 Predation and Parasitism Warning coloration (aposematic)

37 Predation and Parasitism Batesian and Mullerian Mimicry

38 Predation and Parasitism What about plants? Some plants rely on the spatio-temporal variation in abundance they are never very abundant nor predictable in their occurrence

39 Predation and Parasitism Morphological adaptations

40 Predation and Parasitism Their origin may have been by chance, with each combination potentially providing a little better defense As a result, most plants don’t just have a single compound…Why? Most have several, primarily to protect against herbivores, bacteria and/or fungi

41 Predation and Parasitism Most of these chemicals are termed ‘secondary compounds’ because most seem to lack a direct metabolic function, such as those in photosynthesis (also called allelochemics for defense at large)

42 Predation and Parasitism Alkaloids are among the most familiar and addictive drugs known Such drugs as cocaine (from coca), morphine (opium poppy), cannabidiol (hemp), caffeine (teas and coffees), and nicotine (tobacco) There are over 4,000 known alkaloids from >300 families and >7,500 sp About 20% of temperate sp contain them

43 Predation and Parasitism Phenolic compounds are often abundant in plants One group adds the pungency to many of well-known spices and tannins provide the basic compounds used in tanning leather Particularly abundant in oaks and mangroves

44 Predation and Parasitism Saponins are soaplike compounds that are relatively common in tropical plants and act to destroy the fatty component of the cell membrane. Some indigenous people utilize saponins to poison and capture fish, interfering with respiration

45 Predation and Parasitism Cyanogenic Glycosides (cyanide + sugar) When the sugar is digested, the sugar is released leaving the hydrogen cyanide Consequently, these plants are avoided by many species of herbivore

46 Predation and Parasitism Plant breeders have long exploited and taken advantage of ‘artificial selection’ by breeding preferred varieties or traits into crops and/or ornamentals

47 Predation and Parasitism Plant compounds have been utilized as well to control pests (Operopthera brumata)

48 Predation and Parasitism

Download ppt "Predation and Parasitism The potential impact of predation is not questioned In fact, it may be one of the most studied aspects of population/community."

Similar presentations

Ads by Google