Differential Mortality among Red Crossbills (Loxia curvirostra)

The Auk ◽  
1957 ◽  
Vol 74 (1) ◽  
pp. 106-106
Author(s):  
Richard R. Bond
Keyword(s):  
Differential Mortality ◽  
Loxia Curvirostra ◽  
Red Crossbills

scholarly journals Assortative flocking in crossbills and implications for ecological speciation

2012 ◽  
Vol 279 (1745) ◽  
pp. 4223-4229 ◽  
Author(s):  
Julie W. Smith ◽  
Stephanie M. Sjoberg ◽  
Matthew C. Mueller ◽  
Craig W. Benkman
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Ecological Speciation ◽  
Central Question ◽  
Loxia Curvirostra ◽  
Call Type ◽  
Divergent Natural Selection ◽  
Contact Calls ◽  
Red Crossbills

How reproductive isolation is related to divergent natural selection is a central question in speciation. Here, we focus on several ecologically specialized taxa or ‘call types’ of red crossbills ( Loxia curvirostra complex), one of the few groups of birds providing much evidence for ecological speciation. Call types differ in bill sizes and feeding capabilities, and also differ in vocalizations, such that contact calls provide information on crossbill phenotype. We found that two call types of red crossbills were more likely to approach playbacks of their own call type than those of heterotypics, and that their propensity to approach heterotypics decreased with increasing divergence in bill size. Although call similarity also decreased with increasing divergence in bill size, comparisons of responses to familiar versus unfamiliar call types indicate that the decrease in the propensity to approach heterotypics with increasing divergence in bill size was a learned response, and not a by-product of calls diverging pleiotropically as bill size diverged. Because crossbills choose mates while in flocks, assortative flocking could lead indirectly to assortative mating as a by-product. These patterns of association therefore provide a mechanism by which increasing divergent selection can lead to increasing reproductive isolation.

Red Crossbill (Loxia curvirostra)

2020 ◽  
Author(s):  
Craig W. Benkman ◽  
Matthew A. Young
Keyword(s):  
Loxia Curvirostra

Growth, Development and Innate Capacity for Increase in Aphytis Chrysomphali Mercet and A. Melinus Debach, Parasites of California Red Scale, Aonidiella Aurantii (Mask.), In Relation to Temperature.

1974 ◽  
Vol 22 (2) ◽  
pp. 213 ◽  
Author(s):  
I Abdelrahman
Keyword(s):  
Negative Relationship ◽  
Differential Mortality ◽  
Female Progeny ◽  
Annual Fluctuation ◽  
Adaptation To Cold ◽  
Rate Of Increase ◽  
Total Progeny ◽  
Searching Ability ◽  
Pupal Mortality ◽  
Threshold Of Development

A, melinus produced more female progeny and more than twice as many total progeny as A. chrysomphali; it also destroyed almost twice as many hosts through oviposition and mutiliation. A. chrysomphali had a longer post-oviposition period than A. melinus, especially at 30�C. The proportion of single progeny in a host was higher for A, chrysomphali than for A. melinus at all temperatures, and was related to temperature positively in A. chrysomphali and inversely in A. melinus. Large old female A. melinus produced only males at the end of their lives; they did not mate at that stage when offered males, not because they were aged but because they mate only once in their lives. As temperature decreased, female A. melznus ceased producing females earlier, probably because temperature affected either longevity of sperms or the mechanism controlling their release. Differential mortality, temperature, and age of mothers all influenced sex ratio. Pupal mortality was inversely related to temperature within the observed range 20-30�C; in female pupae of A. chrysomphali it was lower than that in either female or male pupae of A. melinus; it was higher in male than female pupae in A. melinus. A. melinus lived longer than A. chrysomphali at all temperatures. Duration of development was longer for A. chrysomphali than for A. melinus at 30�C, but shorter at 20 and 25�C. The threshold of development was 8.5C for A. chrysomphali and 11C for A. melinus. A. chrysomphali had a higher rm at 20 and 25�C than A. melinus, but much lower at 30�C. The highest rate of increase was at > 30�C for A. melinus, and at about 25�C for A. chrysomphali. The rm of the parasites was 3.1-5.0 times that of red scale, depending on parasite species and temperature. A. chrysomphali is smaller than A. melinus, and from the positive relationship between adaptation to cold and speed of development, and the negative relationship between speed of development and size, a negative relationship between size and adaptation to cold within Aphytis spp. may be postulated. A. chrysomphali is more adapted to cold and less to heat than A. melinus. This explains the seasonal and annual fluctuation in their relative abundance in southern Australia. The species would complement each other in controlling red scale; from the data presented here it is possible that Aphytis spp. in Australia may have evolved into more efficient control agents of red scale than elsewhere. Knowledge on the searching ability of Aphytis at different host densities is wanting.

scholarly journals Paternal exposure to a common pharmaceutical (Ritalin) has transgenerational effects on the behaviour of Trinidadian guppies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alex R. De Serrano ◽  
Kimberly A. Hughes ◽  
F. Helen Rodd
Keyword(s):  
Poecilia Reticulata ◽  
Specific Effect ◽  
Differential Mortality ◽  
Paternal Effects ◽  
Transgenerational Effects ◽  
Hyperactivity Disorder ◽  
Male Germline ◽  
Paternal Line ◽  
Chronic Dose ◽  
Male Specific

AbstractEvidence is emerging that paternal effects, the nongenetic influence of fathers on their offspring, can be transgenerational, spanning several generations. Methylphenidate hydrochloride (MPH; e.g. Ritalin) is a dopaminergic drug that is highly prescribed to adolescent males for the treatment of Attention-deficit/hyperactivity disorder. It has been suggested that MPH could cause transgenerational effects because MPH can affect the male germline in rodents and because paternal effects have been observed in individuals taking similar drugs (e.g. cocaine). Despite these concerns, the transgenerational effects of paternal MPH exposure are unknown. Therefore, we exposed male and female Trinidadian guppies (Poecilia reticulata) to a low, chronic dose of MPH and observed that MPH affected the anxiety/exploratory behaviour of males, but not females. Because of this male-specific effect, we investigated the transgenerational effects of MPH through the paternal line. We observed behavioural effects of paternal MPH exposure on offspring and great-grandoffspring that were not directly administered the drug, making this the first study to demonstrate that paternal MPH exposure can affect descendants. These effects were not due to differential mortality or fecundity between control and MPH lines. These results highlight the transgenerational potential of MPH.

Ecological processes maintaining differential tree species distributions in an Australian subtropical rain forest: implications for models of species coexistence

2000 ◽  
Vol 16 (3) ◽  
pp. 387-415 ◽  
Author(s):  
Igor Debski ◽  
David F. R. P. Burslem ◽  
David Lamb
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Rain Forest ◽  
Large Scale ◽  
Species Coexistence ◽  
Common Species ◽  
Size Class ◽  
Differential Mortality ◽  
Mixed Composition ◽  
Large Scale Disturbance

All stems ≥ 1 cm dbh were measured, tagged, mapped and identified on a 1-ha plot of rain forest at Gambubal State Forest, south-east Queensland, Australia. The spatial patterns and size class distributions of 11 common tree species on the plot were assessed to search for mechanisms determining their distribution and abundance. The forest was species-poor in comparison to many lowland tropical forests and the common species are therefore present at relatively high densities. Despite this, only limited evidence was found for the operation of density-dependent processes at Gambubal. Daphnandra micrantha saplings were clumped towards randomly spaced adults, indicating a shift of distribution over time caused by differential mortality of saplings in these adult associated clumps. Ordination of the species composition in 25-m × 25-m subplots revealed vegetation gradients at that scale, which corresponded to slope across the plot. Adult basal area was dominated by a few large individuals of Sloanea woollsii but the comparative size class distributions and replacement probabilities of the 11 common species suggest that the forest will undergo a transition to a more mixed composition if current conditions persist. The current cohort of large S. woollsii individuals probably established after a large-scale disturbance event and the forest has not attained an equilibrium species composition.

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