Egg-size variation and reproductive success in the Herring Gull Lams argentatus: adaptive or constrained size of the last egg?

Herring Gull Larus argentatus eggs from a study colony in the Baltic showed a slight but significant variation in egg size within the laying sequence. Last-laid eggs were only about 5% smaller by volume than first eggs. There was no significant difference in dry yolk weight or dry albumen weight, although possible differences were evident. The chicks had nearly equal hatching weights and equally long tarsi. There was no differential mortality in the third chick in the study colony, and there were no indications of egg-size-mediated mortality. The birds in the colony produced an average of 1.45 fledglings per pair. Compared with several other studied colonies, the difference in egg size within a clutch was low, and a comparison of colonies from northwestern Europe suggests that variance within the clutch is negatively correlated with fledging success, so that a large difference in size between first and last eggs is associated with low fledging success. We suggest that the size of the last egg in the clutch reflects the feeding potential in the environment and is mainly a nonadaptive response to poor feeding conditions during laying.     

The largest land mammal ever imagined

The Oligocene giant rhinocerotoid Indricotherium transouralicum (= Baluchitherium grangeri) , 'the largest mammal that ever lived,' was smaller than is generally believed. Over 90 estimates based on head-and-body length, skull size, molar length and proximal limb bone diameters agree well on a mean mass estimate of about 11 tonnes (t) rather than the 20–30 t given by most texts. A maximum mass estimate between 15 and 20 t seems probable. Marked sexual dimorphism is possible but the material is insufficient to assess the problem properly. The single source of the inflated, widely cited mass estimates seems to be the famous Granger-Gregory-Ziska reconstruction from 1935–36, which was itself inflated by arbitrary, isometric scaling up of individual elements 'to a hypothetical maximum size'. Paraceralherium bugtiense and P. prohorovi seem to have been somewhat smaller than I. transouralicum. The largest indricotheres were similar in size to the largest fossil proboscideans, and extend the known size range of terrestrial mammals marginally if at all.     

Evolutionary history of the Dactylorhiza maculata polyploid complex (Orchidaceae)

Taxonomic complexity may be associated with migration history and polyploidy. We used plastid and nuclear DNA markers to investigate the evolutionary history of the systematically challenging Dactylorhiza maculata polyploid complex. A total of 1833 individuals from 298 populations from throughout Europe were analysed. We found that gene flow was limited between the two major taxa, diploid ssp. fuchsii (including ssp. saccifera) and tetraploid ssp. maculata. A minimum of three autotetraploid lineages were discerned: (1) southern/western ssp. maculata; (2) northern/eastern ssp. maculata; and (3) Central European ssp. fuchsii. The two ssp. maculata lineages, which probably pre‐date the last glaciation, form a contact zone with high genetic diversity in central Scandinavia. Intermediate plastid haplotypes in the contact zone hint at recombination. Central Europe may have been a source area for the postglacial migration for the southern/western lineage of ssp. maculata, as well as for ssp. fuchsii. The northern/eastern lineage of ssp. maculata may have survived the LGM in central Russia west of the Urals. The tetraploid lineage of ssp. fuchsii is indistinguishable from diploid ssp. fuchsii, and is probably of postglacial origin. The Mediterranean region and the Caucasus have not contributed to the northward migration of either ssp. fuchsii or ssp. maculata. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 503–525.     

Development of polymorphic nuclear microsatellite markers for polyploid and diploid members of the orchid genus Dactylorhiza

Dactylorhiza traunsteineri is an allotetraploid species that belongs to the large Dactylorhiza incarnata/maculata polyploid complex of the Eurasian genus Dactylorhiza (Orchidaceae). Here, eight polymorphic microsatellite loci were isolated using selective hybridization according to the FIASCO protocol (fast isolation by AFLP of sequences containing repeats) with slight modifications. The number of alleles per locus ranged from two to seven. All loci were possible to amplify in several other species of Dactylorhiza, using the same primers.     

Discrimination of two Dendronotus species by allozyme electrophoresis and the reinstatement of Dendronotus lacteus (Thompson, 1840) (Nudibranchia, Dendronotoidea)

Whitish and brownish specimens of what has commonly been identified as Dendronotus frondosus (Ascanius, 1774) from the fjord Gullmaren on the Swedish west coast are shown by allozyme electrophoresis to be genetically isolated from each other, and are thus considered to represent two separate species. The brownish specimens are regarded nominally as representing D. frondosus. Dendronotus lacteus (Thompson, 1840) is reinstated for the whitish specimens, and the species is redescribed.     

Nest Predation Management: Effects on Reproductive Success in Endangered Shorebirds

Abstract Many species have suffered population declines through loss of suitable habitat. In addition, current agricultural land use and human settlements favor generalist predators, which pose an increasing threat to ground-nesting bird species such as shorebirds (waders). During the last 2 decades, nest exclosures have been used to control nest-predation rates and often improved hatching success. We evaluated the effectiveness of protective nest-cages to boost reproductive success in the endangered southern dunlin (Calidris alpina schinzii) and ultimately to halt the population decline. We found that exclosures successfully increased the survival probability of nests and, thereby, the number of hatchlings, without markedly elevating the predation rate on incubating adults. Nest exclosures did not, however, translate into an increased number of fledglings and recruits produced/breeding adult in the population, showing that factors other than nest survival are also important for population development. Our results highlight that conservation efforts aimed only at removing high nest-predation pressure may be insufficient to preserve declining species such as the southern dunlin.     

Genetic diversity and differentiation of allopolyploid Dactylorhiza (Orchidaceae) with particular focus on the Dactylorhiza majalis ssp. traunsteineri/lapponica complex

Genetic differentiation of Dactylorhiza majalis ssp. traunsteineri from the Alps, Scandinavia, and Britain was studied and compared with other allotetraploid members of the systematically challenging genus Dactylorhiza . One-hundred and eleven populations from altogether 18 taxa were analysed for eight polymorphic plastid markers and two size-variable fragments from the nuclear internal transcribed spacer (ITS) region. In total, 60 plastid haplotypes and six ITS alleles were found among the 737 individuals analysed. No clear differentiation between populations of ssp. traunsteineri from the three regions was revealed. However, ssp. traunsteineri was genetically differentiated from Dactylorhiza baumanniana , Dactylorhiza elata , and D. majalis ssp. sphagnicola , although the majority of allotetraploid taxa remained inseparable. Judging from the degree of concerted evolution in ITS, D. majalis ssp. alpestris may be regarded as a relatively old allotetraploid, whereas ssp. baltica and ssp. purpurella may be considerably younger. Based on plastid data, the Alp region had the highest genetic diversity followed by Scandinavia and Britain. The geographic distribution of haplotypes provided support for possible refugial areas around the Alps and for several independent immigration routes into Scandinavia after the last ice age.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 52–67.