Do migrant and resident species differ in the timing of increases in reproductive and thyroid hormone secretion and body mass? A case study in the comparison of pre-breeding physiological rhythms in the Eurasian Skylark and Asian Short-toed Lark

Background:Physiological preparation for reproduction in small passerines involves the increased secretion of reproductive hormones, elevation of the metabolic rate and energy storage, all of which are essential for reproduction. However, it is unclear whether the timing of the physiological processes involved is the same in resident and migrant species that breed in the same area. To answer this question, we compared temporal variation in the plasma concentration of luteinizing hormone(LH), testosterone(T), estradiol(E_2), triiothyronine(T_3) and body mass, between a migrant species, the Eurasian Skylark(Alauda arvensis) and a resident species, the Asian Short-toed Lark(Calandrella cheleensis), both of which breed in northeastern Inner Mongolia, China, during the 2014 and 2015 breeding seasons.Methods:Twenty adult Eurasian Skylarks and twenty Asian Short-toed Larks were captured on March 15, 2014 and 2015 and housed in out-door aviaries. Plasma LH, T(males), E_2(females), T_3 and the body mass of each bird were measured every six days from March 25 to May 6.Results:With the exception of T, which peaked earlier in the Asian Short-toed Lark in 2014, plasma concentrations of LH, T, E_2 and T_3 of both species peaked at almost the same time. However, Asian Short-toed Larks attained peak body mass earlier than Eurasian Skylarks. Plasma T_3 concentrations peaked 12 days earlier than plasma LH in both species. Generally, plasma LH, T, E_2, T_3 and body mass, peaked earlier in both species in 2014 than 2015.Conclusions:The timing of pre-reproductive changes in the endocrine system and energy metabolism can be the same in migrant and resident species; however, residents may accumulate energy reserves faster than migrants. Although migration does not affect the timing of pre-breeding reproductive and metabolic changes, migrant species may need more time to increase their body mass. T levels in resident species may be accelerated by higher spring temperatures that may also advance the pre-breeding preparation of both migrants and residents.

Non-breeding movements of the Black-tailed Gull(Larus crassirostris)

With the continued development of tracking technology and increasing interest in animal movement,our understanding of migration behavior has become more comprehensive.However,there are still many species that have not been well studied,particularly sea birds.Here,we present the first year-round Global Positioning System(GPS)tracking data of the Black-tailed Gull(Larus crassirostris)at the population level.We used solar-powered GPS-Global System for Mobile communication(GSM)loggers to successfully track 30 individuals breeding at Xingrentuo Islet,Liaoning Province,China,for 1-3 years.Except for one individual who roamed in the far north of the Yellow Sea during non-breeding period,all others did a directed southward migration.Migration routes and wintering sites differed among migrating gulls and between years for the birds tracked for two or more years.Additionally,during wintering,the migrating gulls were more likely to travel over a large body of water and shift sites,and some trajectories were quite complex,which was probably closely related to what we observed in the field about their boat-chasing behavior.Compared to wintering movements,the post-breeding movements ranged over a smaller area.Specifically,almost all of them had a long post-breeding period near the breeding islet(≥120days,<220 km from the breeding islet),and 80%of the gulls who were tracked more than one year had at least one faithful post-breeding site.Compared to the post-breeding period,only approximately half of the migrating gulls had a pre-breeding period that was shorter(3-20 days)and closer to the breeding islet(≤80 km).Migration distance varied among migrating gulls(range 209-2405 km)and the gulls moved least distance during postbreeding period.Furthermore,we found that the southward movement of the migrating gulls occurred when the temperature near the breeding islet dropped;specifically,the gulls directly migrated southward away from the post-breeding site.Our results suggest that the Black-tailed Gull has a long post-breeding period but a short prebreeding period near the breeding islet and high diversity of their migrating patterns(in especial migration routes and wintering sites).

Genetic Parameters and Correlation between Tomato Late Blight Field Resistance and Fruit Quality

The objective of this study was to estimate genetic parameters and quantify the correlations between late blight (LB) resistance and fruit quality traits in 220 families F2:3, under tropical field conditions. The families were arranged in randomized blocks in field trials, with six resistant inbred lines used as control, in plots of five plants. It evaluated the severity in the middle of the epidemy, final severity, area under the curve of progress of late blight, pH, total soluble solids, titratable acidity and flavor. There is genetic variability for epidemiological variables and total soluble solids. Heritabilities, obtained by parent-offspring regression, were high and indicated the possibility of satisfactory genetics gains and success in the introgression of resistance alleles. The correlations were negative, of high to intermediate magnitude, among the variables area under the curve of progress of late blight, total soluble solids and total titratable acidity.