Vertical transmission in feather mites: insights into its adaptive value

1. The consequences of symbiont transmission strategies are better understood than their adaptive causes. 2. Feather mites are permanent ectosymbionts of birds assumed to be transmitted mainly vertically from parents to offspring. The transmission of Proctophyllodes doleophyes Gaud (Astigmata, Proctophyllodidae) was studied in two European populations of pied flycatchers, Ficedula hypoleuca Pallas (Passeriformes, Muscicapidae). 3. The vertical transmission of this mite species is demonstrated here with an acaricide experiment. This study also compared (for two distant populations during 4 years) patterns in reductions in mite intensity in adult birds, from egg incubation to chick‐rearing periods, with the predictions of three hypotheses on how host survival prospects and mite intraspecific competition might drive feather mites' transmission strategy. 4. The results are in agreement with previous studies and show that feather mites transmit massively from parents to chicks. 5. The magnitude of the transmission was closer to that predicted by the hypothesis based on intraspecific competition, while a bet‐hedging strategy is also partially supported.     

Temporal trends in phenology of the honey bee Apis mellifera (L.) and the small white Pieris rapae (L.) in the Iberian Peninsula (1952–2004)

Abstract.  1. The first adult appearance of two insect species, the honey bee Apis mellifera (L.) and the small white Pieris rapae (L.), was examined between 1952 and 2004 in Spain.
2. After factoring out the variability resulting from the broad geographical and topographical range of the 798 sampling localities, multiple regression models were used to detect temporal trends in phenology.
3. The best models were repeated, including spring temperature as the explanatory variable to examine the effects of climate on appearance phenology.
4. Both species showed similar temporal trends, delaying their appearance phenology until the mid-1970s and advancing it since that time.
5. The appearance times for both species were negatively related to mean temperature between February and April, with both species appearing earlier in years with warmer springs.
6. The strong dependence of appearance dates on temperature indicates that climatic fluctuations are primarily responsible for the inter-annual variability in spring appearance phenology of both species, and consequently account for the observed long-term trends.
7. This study demonstrates that insect phenology is an accurate and sensitive bioindicator of climate change.     

A study of genetic distances and variability in several species pf the gemis Ctenomys (Rodentia: Octodontidae) with special references to a probable causal role of chromosomes in speciation

Genetic variability measured by allozymic electrophoresis has been studied in several species of the subterranean rodent genus Ctenomys (Octodontidae). The study was carried out with the main purpose of analysing a special group known as the 'Corrientes group' which inhabits the province of Corrientes in Argentina. The members of the group are, with high probability, isolated reproductively due to their karyotypic differences diploid numbers are between 42 and 70). To evaluate whether the chromosomal differences were the causes of speciation or if they arose a posteriori, we compared the level of the genetic distance among taxa within the orrientes group with all those measured between intraspecific populations in Ctenomys . The results indicate that the distances among the populations of the Corrientes group are at or below the level of those measured among traspecific populations in Ctenomys . Thus, it is unlikely that genetic differentiation triggered speciation. It is shown that this low level of genetic differentiation is not in contradiction with the high levels expected for species originating from one of the possible mechanisms of chromosomal speciation named, chromosomal transilience. Although for geographical reasons it seems obviousthat gene flow is precluded among the members of the Corrientes group, the Slatkin method for estimating Nm values was also used. Because high values of Nm exist but no isolation by distance could be detected, it is suggested that reproductive and geographical isolation are very ecent. Finally, analysis of population variability suggests that the high levels of heterozygosity observed (a) can be explained by the population structure, and (b) are within the range of expected values if bottlenecks have occurred in the recent history of the Corrientes group. As a general conclusion, the results indicate that in the Corrientes group the genetic data support a putative causal role for chromosomes in speciation.     

An uncommon oyster breeding system in a Late Tertiary Patagonian species

Iribarne, O. O., Pascual, M. S. & Zampatti, E. A. 1990 04 15: An uncommon oyster breeding system in a Late Tertiary Patagonian species. Lethaia , Vol. 23 , pp. 153–156. Oslo. ISSN 0024–1164.
The brooding extant species Ostrea puelchana has a breeding system that is unique among living oysters. Females larger than 55 mm often carry small epidictic males (up to 30 mm) on the anterior edge of the concave shell. These are strongly attached when small, but become relatively less strongly attached as they grow larger. Field experiments show that their growth is retarded as a result of the influence of the carrier. Advantages of this mating system are reflected in the success of fertilization; sperm transfer is facilitated safely during long periods of the oyster's life. A similar attachment pattern was found in a fossil oyster, Ostrea aluarezi , from a Patagonian deppsit. The finding suggests that this particular reproductive strategy had already evolved among late Tertiary ostreids. * Epibiotic. breeding system, fossil , Ostrea alvarezi, oyster, Tertiary .     

Evaluation of Current Population Genetics Theory

My aim is to give a partial evaluation or critique of the stateof population genetics theory. A decent theory must includethe following components: the development of concepts of fitnessthat have demonstrated epistemic correlations, life tables,mating, fecundity, finite (even if large) niche size, and, ofcourse, Mendelism and mutation. It must in the end also includevarying environment and competition between species. The extentto which the desiderata are met is discussed. The big lacunaein the whole theory appear to be the inadequate treatment offitness and the ignoring of niche capacity. Some theorems thatare given as fundamental must be questioned and even discarded.Integration of ideas of simple Mendelism, quantitative geneticvariation, and ecology is the big task ahead. It is criticalthat more complete theory be developed.     

A new species of Lepidasthenia (Polychaeta, Polynoidae) from Canary Islands

Lepidasthenia medanensis spn, is described from subtidal sandy bottom and beds of Cymodoceanodosa on the south west coast of Tenerife, Canary Islands.