Rapid adaptation to invasive predators overwhelms natural gradients of intraspecific variation

Invasive predators can exert strong selection on native populations. If selection is strong enough, populations could lose the phenotypic variation caused by adaptation to heterogeneous environments. We compare frog tadpoles prior to and 14 years following invasion by crayfish. Prior to the invasion, populations differed in their intrinsic developmental rate, with tadpoles from cold areas reaching metamorphosis sooner than those from warm areas. Following the invasion, tadpoles from invaded populations develop faster than those from non-invaded populations. This ontogenetic shift overwhelmed the intraspecific variation between populations in a few generations, to the point where invaded populations develop at a similar rate regardless of climate. Rapid development can have costs, as fast-developing froglets have a smaller body size and poorer jumping performance, but compensatory growth counteracts some costs of development acceleration. Strong selection by invasive species can disrupt local adaptations by dampening intraspecific phenotypic variation, with complex consequences on lifetime fitness

Mono- versus polydrug abuse patterns among publicly funded clients

To examine patterns of mono- versus polydrug abuse, data were obtained from intake records of 69,891 admissions to publicly funded treatment programs in Tennessee between 1998 and 2004. While descriptive statistics were employed to report frequency and patterns of mono- and polydrug abuse by demographic variables and by study years, bivariate logistic regression was applied to assess the probability of being a mono- or polydrug abuser for a number of demographic variables. The researchers found that during the study period 51.3% of admissions reported monodrug abuse and 48.7% reported polydrug abuse. Alcohol, cocaine, and marijuana were the most commonly abused substances, both alone and in combination. Odds ratio favored polydrug abuse for all but one drug category–other drugs. Gender did not affect drug abuse patterns; however, admissions for African Americans and those living in urban areas exhibited higher probabilities of polydrug abuse. Age group also appeared to affect drug abuse patterns, with higher odds of monodrug abuse among minors and adults over 45 years old. The discernable prevalence of polydrug abuse suggests a need for developing effective prevention strategies and treatment plans specific to polydrug abuse

Exploring a Multidimensional Approach to Impulsivity in Predicting College Student Gambling

Impulsivity has been implicated as a contributing factor in the development of gambling problems among college students, but attempts to confirm this relation have been inconsistent. One explanation for these incongruent findings is that impulsivity may be multidimensional and that distinct dimensions differentially predict separate behaviors. Using a large, diverse sample of college students, a factor analysis of self-report measures related to impulsivity revealed a three-factor structure of Behavioral Activation, Preference for Stimulation, and Inhibition Control that was similar to the structure found by Meda and colleagues (2009) in a different adult sample. Low risk gamblers and symptomatic gamblers scored significantly lower on Behavioral Activation and Inhibition Control than non-gamblers. Conversely, low risk gamblers and symptomatic gamblers scored significantly higher on Preference for Stimulation. Prevalence of gambling and gambling activity preference for this sample was also assessed