Counterintuitive migration patterns by Atlantic salmon Salmo salar smolts in a large lake

What little is known about the seaward migration of Salmo salar smolt migration through standing waters indicates that it is both slow and results in high mortality rates, compared with riverine migration. This may be partly because smolts in lakes need to swim more actively and require more complex directional cues than they do in rivers. In this telemetry study of smolt migration through Loch Lomond, S. salar smolts made repeated movements in directions away from the outflowing river, which considerably increased migration time.     

Non-kin cooperation in bats

Many bats are extremely social. In some cases, individuals remain together for years or even decades and engage in mutually beneficial behaviours among non-related individuals. Here, we summarize ways in which unrelated bats cooperate while roosting, foraging, feeding or caring for offspring. For each situation, we ask if cooperation involves an investment, and if so, what mechanisms might ensure a return. While some cooperative outcomes are likely a by-product of selfish behaviour as they are in many other vertebrates, we explain how cooperative investments can occur in several situations and are particularly evident in food sharing among common vampire bats (Desmodus rotundus) and alloparental care by greater spear-nosed bats (Phyllostomus hastatus). Fieldwork and experiments on vampire bats indicate that sharing blood with non-kin expands the number of possible donors beyond kin and promotes reciprocal help by strengthening long-term social bonds. Similarly, more than 25 years of recapture data and field observations of greater spear-nosed bats reveal multiple cooperative investments occurring within stable groups of non-kin. These studies illustrate how bats can serve as models for understanding how cooperation is regulated in social vertebrates.     

A molecular biogeography of the New World cypresses (<Emphasis Type="Italic">Callitropsis</Emphasis>, <Emphasis Type="Italic">Hesperocyparis</Emphasis>; Cupressaceae)

Previous studies of phylogenetic relationships among cypresses have recovered separate Old and New World lineages, resolved a Southeast Asian species sister to the New World clade, and split the New World group into two principal lineages (i.e., the Macrocarpa and Arizonica clades) having fundamentally different geographic distributions. Collectively, these observations suggested a number of intriguing hypotheses regarding the origin and biogeographic history of the New World cypresses (NWC). In this study, we use DNA sequence data to examine the historical biogeography of NWC. Divergence times are estimated in BEAST using fossil-calibrated minimum age constraints, and a spatial history of the group reconstructed using Statistical Dispersal-Vicariance Analysis. Results presented here suggest ancestral NWC colonized the New World from Asia, perhaps by a more widespread trans-Beringian ancestor, in the late Cretaceous or early Cenozoic. Strong positive correlations between species age and geographic location (i.e., latitude and longitude) suggest current distributions were influenced by directional migration (northwest to southeast) as climates cooled and became increasingly arid in the latter half of the Cenozoic. Although our data support a middle Eocene (45 Mya) origin for NWC, nearly all species are apparently no more than late Miocene (6 Mya) in age, and net diversification rates in the group are among the highest reported to date for gymnosperms. Key coastal to interior migrations underlie the fundamentally different biogeographies of the Macrocarpa and Arizonica clades, with the Transverse Ranges of southern California being a barrier to north–south migration of certain species from these two lineages.     

Structural and Biochemical Characterization of the Early and Late Enzymes in the Lignin β-Aryl Ether Cleavage Pathway from Sphingobium sp. SYK-6

There has been great progress in the development of technology for the conversion of lignocellulosic biomass to sugars and subsequent fermentation to fuels. However, plant lignin remains an untapped source of materials for production of fuels or high value chemicals. Biological cleavage of lignin has been well characterized in fungi, in which enzymes that create free radical intermediates are used to degrade this material. In contrast, a catabolic pathway for the stereospecific cleavage of β-aryl ether units that are found in lignin has been identified in Sphingobium sp. SYK-6 bacteria. β-Aryl ether units are typically abundant in lignin, corresponding to 50–70% of all of the intermonomer linkages. Consequently, a comprehensive understanding of enzymatic β-aryl ether (β-ether) cleavage is important for future efforts to biologically process lignin and its breakdown products. The crystal structures and biochemical characterization of the NAD-dependent dehydrogenases (LigD, LigO, and LigL) and the glutathione-dependent lyase LigG provide new insights into the early and late enzymes in the β-ether degradation pathway. We present detailed information on the cofactor and substrate binding sites and on the catalytic mechanisms of these enzymes, comparing them with other known members of their respective families. Information on the Lig enzymes provides new insight into their catalysis mechanisms and can inform future strategies for using aromatic oligomers derived from plant lignin as a source of valuable aromatic compounds for biofuels and other bioproducts.     

Inter and intra‐population phenotypic and genotypic structuring in the European whitefish Coregonus lavaretus,a rare freshwater fish in Scotland

This study revealed between‐lake genetic structuring between Coregonus lavaretus collected from the only two native populations of this species in Scotland, U.K. (Lochs Eck and Lomond) evidenced by the existence of private alleles (12 in Lomond and four in Eck) and significant genetic differentiation (F_ST = 0·056) across 10 microsatellite markers. Juvenile C. lavaretus originating from eggs collected from the two lakes and reared in a common‐garden experiment showed clear phenotypic differences in trophic morphology (i.e. head and body shape) between these populations indicating that these characteristics were, at least partly, inherited. Microsatellite analysis of adults collected from different geographic regions within Loch Lomond revealed detectable and statistically significant but relatively weak genetic structuring (F_ST = 0·001–0·024) and evidence of private alleles related to the basin structure of the lake. Within‐lake genetic divergence patterns suggest three possibilities for this observed pattern: (1) differential selection pressures causing divergence into separate gene pools, (2) a collapse of two formerly divergent gene pools and (3) a stable state maintained by balancing selection forces resulting from spatial variation in selection and lake heterogeneity. Small estimates of effective population sizes for the populations in both lakes suggest that the capacity of both populations to adapt to future environmental change may be limited.     

Freshwater and coastal migration patterns in the silver‐stage eel Anguilla anguilla

The unimpeded downstream movement patterns and migration success of small female and male Anguilla anguilla through a catchment in north‐west Europe were studied using an acoustic hydrophone array along the River Finn and into the Foyle Estuary in Ireland. Twenty silver‐stage A. anguilla (total length, L_T, range: 332–520 mm) were trapped 152 km upstream from a coastal marine sea‐lough outlet and internally tagged with acoustic transmitters of which 19 initiated downstream migration. Migration speed was highly influenced by river flow within the freshwater (FW) compartment. Anguilla anguilla activity patterns were correlated with environmental influences; light, tidal direction and lunar phase all influenced the initiation of migration of tagged individuals. Migration speed varied significantly between upstream and lower river compartments. Individuals migrated at a slower speed in transitional water and sea‐lough compartments compared with the FW compartment. While 88·5% survival was recorded during migration through the upper 121 km of the river and estuary, only 26% of A. anguilla which initiated downstream migration were detected at the outermost end of the acoustic array. Telemetry equipment functioned efficiently, including in the sea‐lough, so this suggests high levels of mortality during sea‐lough migration, or less likely, long‐term sea‐lough residence by silver A. anguilla emigrants. This has important implications for eel management plans.