Trophic Dynamics of a Top Predator, Ambystoma tigrinum nebulosum (Caudata: Ambystomatidae), in a Lentic Community

Copeia ◽  
1987 ◽  
Vol 1987 (4) ◽  
pp. 949 ◽  
Author(s):  
Joseph R. Holomuzki ◽  
James P. Collins
Keyword(s):  
Trophic Dynamics ◽  
Ambystoma Tigrinum ◽  
Top Predator ◽  
Ambystoma Tigrinum Nebulosum

A model of inter-cohort cannibalism and paedomorphosis in Arizona Tiger Salamanders, Ambystoma tigrinum nebulosum

2016 ◽  
Vol 09 (02) ◽  
pp. 1650030
Author(s):  
Maeve L. McCarthy ◽  
Howard H. Whiteman
Keyword(s):  
Periodic Solutions ◽  
Structured Populations ◽  
Unstable Equilibrium ◽  
Ambystoma Tigrinum ◽  
General Applicability ◽  
Previous Theory ◽  
Tiger Salamanders ◽  
Stable Equilibria ◽  
Per Capita ◽  
Ambystoma Tigrinum Nebulosum

Cannibalism is widespread in size-structured populations. If cannibals and victims are in different life stages, dominant cohorts of cannibals can regulate recruitment. Arizona Tiger Salamanders, Ambystoma tigrinum nebulosum, exhibit facultative paedomorphosis in which salamander larvae either metamorphose into terrestrial adults or become sexually mature while still in their larval form. Although many salamanders exhibit cannibalism of larvae, the Arizona Tiger Salamander also exhibits cannibalism of young by the aquatic adults. We formulate a differential equations model of this system under the assumption that the terrestrial adults do not impact the system beyond their contribution to the birth of young larvae. We establish non-negativity, boundedness and persistence of the salamander population under certain assumptions. We consider the equilibrium states of the system in the presence or absence of a birth contribution from the terrestrial or metamorph adults. Constant per capita paedomorphosis leads to asymptotically stable equilibria. The per capita paedomorphosis rate of the larvae must be density dependent in order for periodic solutions to exist. Furthermore, the stage transition rate must be sufficiently decreasing in order to guarantee the existence of an unstable equilibrium. Periodic solutions are only possible in the presence of a unique nontrivial unstable equilibrium. Our results conform to previous theory on paedomorphosis which suggests general applicability of our results to similar systems.

Intraspecific variation in diet within and between trophic morphs in larval tiger salamanders (Ambystoma tigrinum nebulosum)

1984 ◽  
Vol 62 (2) ◽  
pp. 168-174 ◽  
Author(s):  
James P. Collins ◽  
Joseph R. Holomuzki
Keyword(s):  
Intraspecific Variation ◽  
Narrow Range ◽  
Ambystoma Tigrinum ◽  
Tiger Salamanders ◽  
Ambystoma Tigrinum Nebulosum

Larvae of Ambystoma tigrinum nebulosum are dimorphic. The "broad-headed" morph is cannibalistic and has a wider head and enlarged vomerine teeth compared with typical larvae. We collected larvae from tour habitats in Arizona, U.S.A., to quantify how diet varies within and betweeen morphs relative to habitat, and how diet varies relative to age in typical morphs from one habitat. Broad-headed or cannibalistic morphs occurred in both sexes and most of their diet [Formula: see text] was other salamanders. A variety of invertebrates comprised the remainder of their diet. Typical morphs ate primarily macroinvertebrates and plankton, and rarely (1 of 170 larvae analyzed) conspecifics. Young typical larvae consumed a narrow range of prey, mostly plankton, compared with older larvae, which consumed a diversity of macroinvertebrates in addition to plankton. Our results indicate that description of broad-headed larvae as cannibals is justified because most of their diet is other salamanders, while typical morphs rarely eat salamanders. Both morphs also eat invertebrates. With regard to diet in larval A. tigrinum, therefore, "cannibalistic" versus "typical" refers to a predilection and is not an absolute categorization.

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