Global phylogeography and seascape genetics of the lemon sharks (genus Negaprion).

Seascapes are complex environments, and populations are often isolated by factors other than distance. Here we investigate the role of coastal habitat preference and philopatry in shaping the distribution and population structure of lemon sharks. The genus Negaprion comprises the amphiatlantic lemon shark (N. brevirostris), with a relict population in the eastern Pacific, and its Indo-West Pacific sister species, the sicklefin lemon shark (N. acutidens). Analyzing 138 individuals throughout the range of N. brevirostris (N = 80) and N. acutidens (N = 58) at microsatellite loci (nine and six loci, respectively) and the mitochondrial control region, we find evidence of allopatric speciation corresponding to the Tethys Sea closure (10-14 million years ago) and isolation of the eastern Pacific N. brevirostris population via the emergence of the Isthmus of Panama (approximately 3.5 million years ago). There is significant isolation by oceanic distance (R(2) = 0.89, P = 0.005), defined as the maximum distance travelled at depths greater than 200 m. We find no evidence for contemporary transatlantic gene flow (m, M = 0.00) across an oceanic distance of approximately 2400 km. Negaprion acutidens populations in Australia and French Polynesia, separated by oceanic distances of at least 750 km, are moderately differentiated (F(ST) = 0.070-0.087, P < or = 0.001; Phi(ST) = 0.00, P = 0.99), with South Pacific archipelagos probably serving as stepping stones for rare dispersal events. Migration between coastally linked N. brevirostris populations is indicated by nuclear (m = 0.31) but not mitochondrial (m < 0.001) analyses, possibly indicating female natal site fidelity. However, philopatry is equivocal in N. acutidens, which has the lowest control region diversity (h = 0.28) of any shark yet studied. Restricted oceanic dispersal and high coastal connectivity stress the importance of both local and international conservation efforts for these threatened sharks.

[Who will take care of my children?]. / Quien cuidara de mis hijos?

AIDS: HIV-positive parents face difficult decisions in evaluating their own health status and their children's future. Parents whose children have been placed in alternate homes must cooperate with the state to regain custody. The state must help parents by assisting them with securing decent housing and rehabilitation, and developing skills in child rearing. There are many forms of custody available to ill parents. Guardians can be appointed by a family court. A Deed of Guardianship directs the court regarding the parent's choice of guardian. Stand-By Guardianship (available in FL, NY, IL, and CT) allows the guardian to assume responsibility for a child only as needed or when the parent dies. Foster care is another option, but many HIV-positive parents feel it is unfair. Foster parents are given a stipend for the care of the child, generally greater than benefits afforded the natural parent. Parents may name a guardian for a child in their will and the court will weigh their wishes in the final custody decision. Parents should discuss all options with an attorney prior to choosing how to ensure their children's well-being.^ieng