Conservation implications of adaptation to tropical climates from a historical perspective

Tropical climates and the biodiversity associated with them have long interested natural historians. Alexander von Humboldt inspired a generation of scientists, such as Charles Darwin and Alfred Russel Wallace, to observe and study tropical ecosystems. More recently, the mid‐20th century saw Theodosius Dobzhansky and Daniel Janzen lay the foundations for studying adaptation to tropical climates. Now in the 21st century, we are beginning to realize the threats posed by current and future climate change to tropical populations which, despite relatively low levels of projected warming for low‐latitude regions, face potentially significant detrimental impacts. Building on the insights of researchers in decades and centuries past, improved understanding of tropical ecology, evolution and biogeography will help us to conceive how future global change will impact on biodiversity.     

First record of an epibiosis between the sand crab Emerita analoga (Stimpson, 1857) (Decapoda: Hippidae) and the mussel Semimytilus algosus (Gould, 1850) (Bivalvia, Mytilidae) in southern Peru

Coastal zones of the Humboldt Current Upwelling System (HCUS) are composed both of rocky and sandy beaches inhabited by macrozoobenthic communities. These show oscillating changes in the dominance of species; the abundance of the sand crab Emerita analoga is linked to phases of the El Niño Southern Oscillation (ENSO). The biogenic surfaces of these crabs serve as substrate for opportunistic colonizers. This study is the first record of an epibiosis between E. analoga and the rock mussel Semimytilus algosus, detected at a southern Peruvian sandy beach. Mussels fouled a wide size-range of adult E. analoga (7.3%) but they themselves belonged to small-size classes. The largest S. algosus was 17.4 mm in length. Highest permanence of epibionts was found on larger sand crabs (maximum between 24 and 27 mm). Significantly more mussels were found on the ventral surface (39.4%) compared to 10 other surface areas of the sand crab. Possible benefits and disadvantages of the observed epibiosis for both the basibiont and the epibiont are discussed.     

洪氏环企鹅骨骼的解剖学特点

采用解剖学方法对1只雄性洪氏环企鹅(Spheniscus,humboldti)骨骼系统进行了详细的观察、描述.结果表明:企鹅骨骼结实、沉重不充气;喙长,前端略下弯,颞部呈深凹陷状;肩胛骨及胸骨龙骨突发达;胸椎不愈合;前肢骨骼扁平,特化为鳍状,翼内关节活动性较小,第一掌骨及拇指消失;髌骨发达,跗跖骨短而宽扁.这些特征主要体现了洪氏环企鹅对海中潜水、游泳、取食以及陆地直立的适应.     

Counterintuitive effects of global warming‐induced wind patterns on primary production in the Northern Humboldt Current System

It has been hypothesized that global warming will strengthen upwelling‐favorable winds in the Northern Humboldt Current System (NHCS) as a consequence of the increase of the land–sea thermal gradient along the Peruvian coast. The effect of strengthened winds in this region is assessed with the use of a coupled physical–biogeochemical model forced with projected and climatological winds. Strengthened winds induce an increase in primary production of 2% per latitudinal degree from 9.5°S to 5°S. In some important coastal upwelling sites primary production is reduced. This is due to a complex balance between nutrient availability, nutrient use efficiency, as well as eddy‐ and wind‐driven factors. Mesoscale activity induces a net offshore transport of inorganic nutrients, thus reducing primary production in the coastal upwelling region. Wind mixing, in general disadvantageous for primary producers, leads to shorter residence times in the southern and central coastal zones. Overall, instead of a proportional enhancement in primary production due to increased winds, the NHCS becomes only 5% more productive (+5 mol C m^?2 year^?1), 10% less limited by nutrients and 15% less efficient due to eddy‐driven effects. It is found that regions with a initial strong nutrient limitation are more efficient in terms of nutrient assimilation which makes them more resilient in face of the acceleration of the upwelling circulation.     

Changes in glycolytic enzyme levels and isozyme expression in human lymphocytes during blast transformation.

The levels of each of the glycolytic enzymes were observed to exhibit a parallel increase of 200 to 300% when human lymphocytes were stimulated to undergo blast transformation. A series of electrofocusing and electrophoretic studies was utilized to assess the isozyme distribution of the glycolytic enzymes during blastogenesis. Hexokinase (pI = 7.40), glucosephosphate isomerase (pI = 9.35), and enolase (pI = 8.30) existed as single electrophoretic components and were unchanged during blast transformation. Phosphoglycerate mutase was observed to exist as two isozymes (pI = 5.80 and 6.63), which were also unchanged by blastogenesis. Aldolase, which was present as two electrophoretic forms in lymphocytes (pI = 9.25 and 8.75), exhibited a shift in the relative content of each. In addition to the lactate dehydrogenase isozymes at pI 9.50 and 7.60 found in lymphocytes, lymphoblasts contained isozymes with pI values of 7.30, 7.05, and 5.85. Although glyceraldehyde 3-phosphate dehydrogenase was present as a single electrophoretic form (pI ? 8.0) in both lymphocytes and lymphoblasts, the association of the enzyme with actin produced electrophoretic artifacts with lower pI values. Phosphoglycerate kinase, which appeared as a single form in lymphocytes (pI = 9.00), was present as two isozymes (9.00 and 8.74) in lymphoblasts. Similarly, pyruvate kinase (pI = 8.73 and 8.50 in lymphocytes) exhibited additional isozymes (pyruvate kinase, pI = 7.60 and 5.85, and triosephosphate isomerase, pI = 5.20) as a result of cell transformation.     

Analysis of the sequence variations in the Mhc DRB1-like gene of the endangered Humboldt penguin (Spheniscus humboldti)

The Major Histocompatibility Complex (Mhc) genomic region of many vertebrates is known to contain at least one highly polymorphic class II gene that is homologous in sequence to one or other of the human Mhc DRB1 class II genes. The diversity of the avian Mhc class II gene sequences have been extensively studied in chickens, quails, and some songbirds, but have been largely ignored in the oceanic birds, including the flightless penguins. We have previously reported that several penguin species have a high degree of polymorphism on exon 2 of the Mhc class II DRB1-like gene. In this study, we present for the first time the complete nucleotide sequences of exon 2, intron 2, and exon 3 of the DRB1-like gene of 20 Humboldt penguins, a species that is presently vulnerable to the dangers of extinction. The Humboldt DRB1-like nucleotide and amino acid sequences reveal at least eight unique alleles. Phylogenetic analysis of all the available avian DRB-like sequences showed that, of five penguin species and nine other bird species, the sequences of the Humboldt penguins grouped most closely to the Little penguin and the mallard, respectively. The present analysis confirms that the sequence variations of the Mhc class II gene, DRB1, are useful for discriminating among individuals within the same penguin population as well those within different penguin population groups and species.The nucleotide sequence and amino acid sequence data reported in this paper have been submitted to the DDBJ database and have been assigned the accession numbers AB088371–AB088374, AB089199, AB154393–AB154399, and AB162144.