Predation in an Experimental Protozoan Population (Woodruffia‐Paramecium)

Abstract

Introductory remarks The stimulus to hunt The hunting process .. Selection of hunting site Searching rate Kind of prey attacked The rate of capture by an individual predator Percent time spent hunting ......... Frequency of attacks Percentage of successful attacks Responses to changes in prey density Responses of predators to changes in their density Interspecific relations between predators Mathematical descriptions of predation Resume METHODS 113 114 Tests of the experimental procedure Measurement of searching rate RESULTS .... Searching rate Rate of capture Percent of time spent hunting Frequency and success of attacks The stimulus to attack Responses to changes in prey density Responses to changes in their own density Predation rate Rate of increase Woodruffia-Paramecium cycles DISCUSSION Woodruffia as a predator Comparison of the Woodruffia results with cepted generalizations Hunger as a stimulus for hunting Searching rate .

Organization of a Plant‐Arthropod Association in Simple and Diverse Habitats: The Fauna of Collards (Brassica Oleracea)

“…As a result, relatively stable populations of generalized predators and parasites can persist in these habitats because they can exploit the wide variety of herbivores which become available at different times or in different microhabitats. The shifting of predation pressure in response to changes in prey populations and its various implications have been considered by MacArthur ( 1955), Tin bergen (1960) , Paine (1963Paine ( , 1969, Holling (1965), Salt (1967), Murdoch (1969), and several others. Similarly, specialized predators and parasites are less likely to fluctuate widely because the refuge provided by a complex environment enables their prey I host species to escape widespread annihilation (e.g., Huffaker 1958, Pimentel, Nagel, andMadden 1963).…”

The role of heterotrophic microflagellates in plankton communities

“…Previous studies have noted that at least some bacterivorous ciliates will cease feeding if the bacterial concentration falls below a critical "threshold" concentration (Salt, 1967;Hamilton & Preslan, 1970;Herk et al, 1976;Fenchel, 1980a). This behavior is presumably a mechanism to conserve pm (no.…”

“…In addition, experimental studies have indicated that greater densities of bacteria then are normally present in the plankton are required in order to maintain the growth of ciliates (Berk et a1., 1976;Taylor, 1978;Fenche1, 1980b). Ciliated protozoa have been shown to have definite feeding "thresholds·· of bacterial density below which feeding activity does not take place (Salt, 1967;Hami1iton & Pres1an, 1970;Berk et a1., 1976; Threshold values obtained for laboratory experiments with ciliates -1 bacteria m1 ) have generally been higher than densities of bacteria in most oceanic plankton communities. Fenche1 (1980b) argued that at low bacterial densities (i.e.…”

Oscillations of laboratory populations of the polychaete Capitella capitata (Type I): their cause and implications for natural populations

“…In addition, simulations of population dynamics using a variety of population growth models (Caswell, 1972; , 1979Tanner, 1975;Hassell et al, 1976) established a theoretical basis for cycles, and numerous laboratory studies of single species populations confirmed their existence. Many of the early descriptions of population oscillations were from studies of field populations of small mammals such as lemmings (Shelford, 1943;Pitelka, 1973), lynx (Elton, 1942) and hare (MacLulic, 1937) but examples exist for field populations of insects (Bigger, 1976) and for laboratory populations such as blowflies (Nicholson, 1950), bacteria (Hamson, 1973), cladocerans (Pratt, 1943;Slobodkin, 1954), houseflies (Taylor and Sokal, 1976), mites (Huffaker, 1958), protozoans (Salt, 1967) and rotifers (Halbach, 1978). Studies of single species populations in the laboratory provide much of the knowledge of population oscillations.…”