Does variation in movement tactics and trophic interactions among American alligators create habitat linkages?

1. Highly mobile top predators are hypothesized to spatially and/or temporally link disparate habitats through the combination of their movement and feeding patterns, but recent studies suggest that individual specialization in habitat use and feeding could keep habitats compartmentalized. 2.  We used passive acoustic telemetry and stable isotope analysis to investigate whether specialization in movement and feeding patterns of American alligators (Alligator mississippiensis) in an oligotrophic subtropical estuary created habitat linkages between marine and estuarine/freshwater food webs. 3.  Individual alligators adopted one of the three relatively distinct movement tactics that were linked to variation in diets. Fifty-six per cent of alligators regularly travelled from the upstream (freshwater/mid-estuary) areas into the downstream (marine-influenced) areas where salinities exceed those typically tolerated by alligators. Thirty-one per cent of the alligators made regular trips from the mid-estuarine habitat into the upstream habitat; 13% remained in the mid-estuary zone year-round. 4.  Stable isotopic analysis indicated that, unlike individuals remaining in the mid-estuary and upstream zones, alligators that used the downstream zone fed at least partially from marine food webs and likely moved to access higher prey abundance at the expense of salt stress. Therefore, ‘commuting’ alligators may link marine food webs with those of the estuary and marshes in the coastal Everglades and create an upstream vector for allochthonous nutrient inputs into the estuary. 5.  This study lends further support to the hypothesis that large-bodied highly mobile predators faced with trade-offs are likely to exhibit individual specialization leading to habitat linkages, rather than compartmentalization. However, the conditions under which this scenario occurs require further investigation.

Perceivers' impressions of self -presentation tactics: The effects of age and gender

Eighty-four young and 84 older men and women participants, read scenarios in which a male or female target uses either a self-enhancement or a self-deprecation tactic to present him/herself in front of either a close friend or a new acquaintance. Then participants i.e., perceivers) rated their impressions of the self-enhancing or self-deprecating target on six scales: likable, self-knowledgeable, honest, depressed, happy, and anxious. Overall, both young and old perceivers gave more favorable ratings to self-enhancing targets than to self-deprecating targets. Both young and old perceivers' impressions did not differ for a target who presented him/herself in front of a friend or in front of an acquaintance. Also, perceivers completed Singelis' (1994) Self-Construal Measurement, which measures both interdependent and independent self-construals. As predicted, older perceivers had a higher level of interdependent self-construal than did young perceivers. Unexpectedly, female perceivers had a higher level of independent self-construal than did male perceivers. Neither the age-related nor gender-related differences in self-construals were associated with any age-related or gender-related differences in perceivers' impressions of the self-enhancing and self-deprecating targets. That is, the moderator effects of self-construals on the relationships between self-presentation tactic conditions and ratings of targets were not-significant. ^