Food restriction affects circadian and photoperiodic response in black-headed munia (Lonchura malacca malacca)

We determined the effect of food restriction on locomotor activity pattern and gonadal growth on black-headed munia (Lonchura malacca malacca) exposed to12L:12D light–dark cycle. Two groups of male and female munia (n = 5 pairs each) were exposed to 12L:12D (L = 265 lux; D = 0.3 lux) for day 1–7. On day 8, group one received 4 h food (ZT 0–4; ZT 0 = Zeitgeber time, light onset) and group two received food ad libitum (ZT 0–24 h). Locomotor activity pattern and gonadal growth were recorded over the experiment period of one year. Birds were highly active in group one, with a high daily and total activity. However, activity behavior was fully synchronized with light onset in the group two, when food was available ad libitum. Gonadal maturation was initiated in both the groups but the maturation of testis and ovarian follicle was noticed only in group two (food ad libitum). It appears that food restriction affects the locomotor activity and gonadal growth in black-headed munia.     

Decreasing photoperiods and the testicular cycle of a subtropical bird (spotted Munia), Lonchura punctulata

Abstract

The testicular cycle of subtropical Spotted Munia was studied over a period of 11 months in the following schedules: L/D: 0.25/23.75; L/D: 1/23; L/D: 3/21; L/D: 5/19; L/D: 8/16 and near‐complete darkness. All schedules completely abolished annual gonadal regression with the exception of L/D: 8/16 and near‐complete darkness. In the former, gonads regressed but entered the next reproductive cycle 4 months earlier than the normal scheduled time. In the latter also the cycle was completed though it was sharp and short. It was observed that the greater the duration of the dark period the better the gonadal response is. Sensitivity to short photoperiods/long dark periods seems to be characteristic of the low‐latitude birds; what relevance it has to the normal reproductive cycle of munias in nature is not known.     

四川南充市区白腰文鸟的巢址选择与雏鸟的生长发育

20 0 2年 1 1月～ 2 0 0 4年 4月在四川省南充市区内对白腰文鸟 (Lonchurastriata)的繁殖习性进行了研究。结果表明 ,白腰文鸟 2月下旬开始繁殖 ;影响巢址选择的主要因素 9种 ;雌雄参与筑巢 ,营巢期 5～ 6d;雌雄轮流孵卵 ,孵卵期 1 3～ 1 5d ,整个种群的孵卵高峰期在 4～ 6月 ,窝卵数 (5 .61± 0 . 78) (n =1 8)枚 ,孵化率 86 0 7% ;雌雄均参与育雏 ,育雏期 1 8～ 2 1d ,雏离巢率 82 43 % ,繁殖生产力 3. 0 1 ,育雏两个高峰期 :上午 8:0 0～ 1 0 :0 0时和下午 1 6:0 0～ 1 8:0 0时 ,日育雏次数 (1 2 . 77± 6 .0 7) (n =3 4) ,育雏时间间隔(0 . 96± 0 . 42 )h(n =1 61 ) ;雏鸟形态生长曲线呈“S”型。     

Daily Increments of Light Hours Near Vernal Equinox Synchronize Circannual Testicular Cycle of Tropical Spotted Munia

In some long-lived organisms, particularly in tropical birds and migrants that spend part of the year close to the equator, endogenous circannual rhythms have been demonstrated in seasonal events like reproduction, molt, and migration. These, like the circadian rhythms, are expressed only in constant conditions of illumination with a periodicity deviating from 1 yr. If birds followed this periodicity, they would soon be out of phase with the annual calendar and perish and, therefore, they would need to be synchronized. However, almost nothing is known as to how synchronization is achieved in birds. Herein, with the help of a suitable model, viz., the tropical spotted munia and long-term experiments conducted in series over a 5-yr period, we provide direct evidence for the first time indicating that the segment of annual photocycle with maximal rate of increase prior to vernal equinox (approximately between mid-February and mid-March) synchronizes the circannual reproductive cycle with the monsoon period of ample food supply through a phase delay. Data also indicate, contrary to the prevalent view, that birds in the tropics can perceive minor changes in day-length, that birds respond to progressive changes in day-length as distinct from responding to fixed photoperiods of particular durations, and that birds can actually distinguish the quality of the environmental signal, viz., vernal equinox from early spring, or increasing days of spring from decreasing days of autumn. The underlying mechanisms, although yet to be identified, appear to involve a gonado-inhibitory rather than the conventional gonado-stimulatory response to increasing day-length. The photoperiodic responses of spotted munia are distinctly different from that of any “long-day” birds described thus far and do not conform to the prevalent “circadian coincidence” hypothesis of photoperiodism.     

Daily Increments of Light Hours Near Vernal Equinox Synchronize Circannual Testicular Cycle of Tropical Spotted Munia

In some long-lived organisms, particularly in tropical birds and migrants that spend part of the year close to the equator, endogenous circannual rhythms have been demonstrated in seasonal events like reproduction, molt, and migration. These, like the circadian rhythms, are expressed only in constant conditions of illumination with a periodicity deviating from 1 yr. If birds followed this periodicity, they would soon be out of phase with the annual calendar and perish and, therefore, they would need to be synchronized. However, almost nothing is known as to how synchronization is achieved in birds. Herein, with the help of a suitable model, viz., the tropical spotted munia and long-term experiments conducted in series over a 5-yr period, we provide direct evidence for the first time indicating that the segment of annual photocycle with maximal rate of increase prior to vernal equinox (approximately between mid-February and mid-March) synchronizes the circannual reproductive cycle with the monsoon period of ample food supply through a phase delay. Data also indicate, contrary to the prevalent view, that birds in the tropics can perceive minor changes in day-length, that birds respond to progressive changes in day-length as distinct from responding to fixed photoperiods of particular durations, and that birds can actually distinguish the quality of the environmental signal, viz., vernal equinox from early spring, or increasing days of spring from decreasing days of autumn. The underlying mechanisms, although yet to be identified, appear to involve a gonado-inhibitory rather than the conventional gonado-stimulatory response to increasing day-length. The photoperiodic responses of spotted munia are distinctly different from that of any “long-day” birds described thus far and do not conform to the prevalent “circadian coincidence” hypothesis of photoperiodism.     

Diurnal Profiles of Blood Glucose in Relation to Time of Administration of Melatonin in Male Spotted Munia (Lonchura punctulata)

The study was aimed at demonstration of the effect of a single acute dose of melatonin (0.5 mg/ 100 g body wt.) on the diurnal profile of blood glucose in male spotted munia in relation to the administration of hormone at the onset of light (i.e., at 06.00 h) or at the onset of darkness (i.e., at 18.00 h) under natural photoperiodic (~12L : 12D) conditions. Blood samples from all birds belonging to the control, sham-control (administered only with the vehicle of hormone, i.e., ethanol-saline 1:9 v/v), and melatonin treated groups were collected at four time points, i.e. 06.00 h, 12.00 h, 18.00 h, and 24.00 h, in a 24 hour cycle. The blood glucose levels in control and sham-control birds showed marked variation with regard to the time of sampling, with a mid-day peak and morning nadir. Exogenous melatonin induced a significant alteration in this diurnal pattern of blood glucose with a marked variation in relation to the time of administration of melatonin. While morning administration of melatonin resulted in hypoglycemia at 12.00 h and 24.00 h and hyperglycemia at 18.00 h, the response to evening injection of melatonin was only hypoglycemic at 24.00 h leaving the glycemic values at other time-points almost unaltered compared to the blood glucose levels in control and sham-control munias. The results of this investigation demonstrate for the first time that a schedule of morning administration of melatonin induces a more broad range of variations in the blood glucose levels than a schedule of evening administration does.     

Diurnal Profiles of Blood Glucose in Relation to Time of Administration of Melatonin in Male Spotted Munia (Lonchura punctulata)

The study was aimed at demonstration of the effect of a single acute dose of melatonin (0.5 mg/ 100 g body wt.) on the diurnal profile of blood glucose in male spotted munia in relation to the administration of hormone at the onset of light (i.e., at 06.00 h) or at the onset of darkness (i.e., at 18.00 h) under natural photoperiodic (~12L : 12D) conditions. Blood samples from all birds belonging to the control, sham-control (administered only with the vehicle of hormone, i.e., ethanol-saline 1:9 v/v), and melatonin treated groups were collected at four time points, i.e. 06.00 h, 12.00 h, 18.00 h, and 24.00 h, in a 24 hour cycle. The blood glucose levels in control and sham-control birds showed marked variation with regard to the time of sampling, with a mid-day peak and morning nadir. Exogenous melatonin induced a significant alteration in this diurnal pattern of blood glucose with a marked variation in relation to the time of administration of melatonin. While morning administration of melatonin resulted in hypoglycemia at 12.00 h and 24.00 h and hyperglycemia at 18.00 h, the response to evening injection of melatonin was only hypoglycemic at 24.00 h leaving the glycemic values at other time-points almost unaltered compared to the blood glucose levels in control and sham-control munias. The results of this investigation demonstrate for the first time that a schedule of morning administration of melatonin induces a more broad range of variations in the blood glucose levels than a schedule of evening administration does.     

Effects of Pinealectomy and Exogenous Melatonin on the Thyroid Gland Activity Varies in Relation to Reproductive Status of Male Spotted Munia (Lonchura punctulata; Aves,Passeriformes)

The purpose of this investigation was to explore whether the pineal organ and its hormone melatonin has any influence on the activity of thyroid glands, if so, how that relates to the reproductive status of a hitherto unstudied seasonally breeding wild bird. Accordingly, an identical experimental regimen was followed with adult male spotted munia (Lonchura punctulata; Passeriformes) during both its gametogenically active (August-September) and inactive (March-April) phases of the annual reproductive cycle. In either case, the levels of circulating thyroid hormones (both T₃ and T₄) and cellular characteristics of thyroid glands in groups of birds were studied following surgical removal of the pineal gland and/or daily afternoon administration of melatonin (10 μg/ 100 g body weight/ day for 30 days). The results of the same experimental schedule were found to be different depending on the sexual status of the concerned birds. During the breeding phase, pinealectomy (Px) induced significantly decreased values of T₃ and increased for T₄ along with hypertrophy of the thyroid follicular cells (TFC). The changes were reversed in melatonin treated Px birds. An increased amount of T₃ and decreased concentration of serum T₄ were also observed in melatonin injected intact birds. Conversely, the responses of TFC and of thyroid hormones in blood to either Px, or Px with melatonin, or to melatonin alone in intact munias during their inactive reproductive phase were just opposite to those noted during the breeding phase. The results of the present study suggest an influence of the pineal upon the thyroid in spotted munia. Moreover, it appears that this influence is carried out by melatonin, the action of which is reversible in relation with the gametogenic status of the concerned avian species.     

Song Learning in Wild and Domesticated Strains of White‐Rumped Munia,Lonchura striata,Compared by Cross‐Fostering Procedures: Domestication Increases Song Variability by Decreasing Strain‐Specific Bias

Song diversity results from the interactions between natural selection, sexual selection, and individual learning. To understand song diversity, all three factors must be considered collectively, not separately. Bengalese Finches were domesticated about 250 yr ago. Their courtship songs have become different from their ancestor, the White‐rumped Munia. Bengalese Finches sing songs with complex note‐to‐note transition patterns and with acoustically diverse song notes while White‐rumped Munias sing songs with fixed note sequence and mostly broad band song notes. Bengalese Finches were selected for domestication based on their good parenting ability, not their songs, but this artificial selection has nonetheless affected their songs. To test whether divergence occurred not only in the song phenotypes but also in the genetic basis for predisposition of strain specific song learning, we conducted a cross‐fostering experiment between Bengalese Finches and White‐rumped Munias. In both strains, song learning was affected by rearing condition: the acoustical feature and transition patterns followed those of the foster fathers. However, the accuracy of song learning differed between the wild and the domesticated strains: sharing of song note between sons and tutors in Finches was not very accurate regardless of the tutor, while Munias were highly accurate in copying Munia songs but often omitted song elements from Finch fathers. These results suggest that White‐rumped Munias are strongly constrained to learn their own strain’s song, and that this constraint was relaxed in the Bengalese Finch by domestication.     

On the origin of the Hirudinea and the demise of the Oligochaeta

The phylogenetic relationships of the Clitellata were investigated with a data set of published and new complete 18S rRNA gene sequences of 51 species representing 41 families. Sequences were aligned on the basis of a secondary structure model and analysed with maximum parsimony and maximum likelihood. In contrast to the latter method, parsimony did not recover the monophyly of Clitellata. However, a close scrutiny of the data suggested a spurious attraction between some polychaetes and clitellates. As a rule, molecular trees are closely aligned with morphology-based phylogenies. Acanthobdellida and Euhirudinea were reconciled in their traditional Hirudinea clade and were included in the Oligochaeta with the Branchiobdellida via the Lumbriculidae as a possible link between the two assemblages. While the 18S gene yielded a meaningful historical signal for determining relationships within clitellates, the exact position of Hirudinea and Branchiobdellida within oligochaetes remained unresolved. The lack of phylogenetic signal is interpreted as evidence for a rapid radiation of these taxa. The placement of Clitellata within the Polychaeta remained unresolved. The biological reality of polytomies within annelids is suggested and supports the hypothesis of an extremely ancient radiation of polychaetes and emergence of clitellates.     

On the ontogeny of the haptor and the evolution of the Monogenea

Data on the ontogeny of the posterior haptor of monogeneans were obtained from more than 150 publications and summarised. These data were plotted into diagrams showing evolutionary capacity levels based on the theory of a progressive evolution of marginal hooks, anchors and other attachment components of the posterior haptor in the Monogenea (Malmberg, 1986). 5 + 5 unhinged marginal hooks are assumed to be the most primitive monogenean haptoral condition. Thus the diagrams were founded on a 5 + 5 unhinged marginal hook evolutionary capacity level, and the evolutionary capacity levels of anchors and other haptoral attachement components were arranged according to haptoral ontogenetical sequences. In the final plotting diagram data on hosts, type of spermatozoa, oncomiracidial ciliation, sensilla pattern and protonephridial systems were also included. In this way a number of correlations were revealed. Thus, for example, the number of 5 + 5 marginal hooks correlates with the most primitive monogenean type of spermatozoon and with few sensillae, many ciliated cells and a simple protonephridial system in the oncomiracidium. On the basis of the reviewed data it is concluded that the ancient monogeneans with 5 + 5 unhinged marginal hooks were divided into two main lines, one retaining unhinged marginal hooks and the other evolving hinged marginal hooks. Both main lines have recent representatives at different marginal hook evolutionary capacity levels, i.e. monogeneans retaining a haptor with only marginal hooks. For the main line with hinged marginal hooks the name Articulon-choinea n. subclass is proposed. Members with 8 + 8 hinged marginal hooks only are here called Proanchorea n. superord. Monogeneans with unhinged marginal hooks only are here called Ananchorea n. superord. and three new families are erected for its recent members: Anonchohapteridae n. fam., Acolpentronidae n. fam. and Anacanthoridae n. fam. (with 7 + 7, 8 + 8 and 9 + 9 unhinged marginal hooks, respectively). Except for the families of Articulonchoinea (e.g. Acanthocotylidae, Gyrodactylidae, Tetraonchoididae) Bychowsky's (1957) division of the Monogenea into the Oligonchoinea and Polyonchoinea fits the proposed scheme, i.e. monogeneans with unhinged marginal hooks form one old group, the Oligonchoinea, which have 5 + 5 unhinged marginal hooks, and the other group form the Polyonchoinea, which (with the exception of the Hexabothriidae) has a greater number (7 + 7, 8 + 8 or 9 + 9) of unhinged marginal hooks. It is proposed that both these names, Oligonchoinea (sensu mihi) and Polyonchoinea (sensu mihi), will be retained on one side and Articulonchoinea placed on the other side, which reflects the early monogenean evolution. Except for the members of Ananchorea [Polyonchoinea], all members of the Oligonchoinea and Polyonchoinea have anchors, which imply that they are further evolved, i.e. have passed the 5 + 5 marginal hook evolutionary capacity level (Malmberg, 1986). There are two main types of anchors in the Monogenea: haptoral anchors, with anlages appearing in the haptor, and peduncular anchors, with anlages in the peduncle. There are two types of haptoral anchors: peripheral haptoral anchors, ontogenetically the oldest, and central haptoral anchors. Peduncular anchors, in turn, are ontogenetically younger than peripheral haptoral anchors. There may be two pairs of peduncular anchors: medial peduncular anchors, ontogentically the oldest, and lateral peduncular anchors. Only peduncular (not haptoral) anchors have anchor bars. Monogeneans with haptoral anchors are here called Mediohaptanchorea n. superord. and Laterohaptanchorea n. superord. or haptanchoreans. All oligonchoineans and the oldest polyonchoineans are haptanchoreans. Certain members of Calceostomatidae [Polyonchoinea] are the only monogeneans with both (peripheral) haptoral and peduncular anchors (one pair). These monogeneans are here called Mixanchorea n. superord. Polyonchoineans with peduncular anchors and unhinged marginal hooks are here called the Pedunculanchorea n. superord. The most primitive pedunculanchoreans have only one pair of peduncular anchors with an anchor bar, while the most advanced have both medial and lateral peduncular anchors; each pair having an anchor bar. Certain families of the Articulonchoinea, the Anchorea n. superord., also have peduncular anchors (parallel evolution): only one family, the Sundanonchidae n. fam., has both medial and lateral peduncular anchors, each anchor pair with an anchor bar. Evolutionary lines from different monogenean evolutionary capacity levels are discussed and a new system of classification for the Monogenea is proposed.In agreeing to publish this article, I recognise that its contents are controversial and contrary to generally accepted views on monogenean systematics and evolution. I have anticipated a reaction to the article by inviting senior workers in the field to comment upon it: their views will be reported in a future issue of this journal. EditorIn agreeing to publish this article, I recognise that its contents are controversial and contrary to generally accepted views on monogenean systematics and evolution. I have anticipated a reaction to the article by inviting senior workers in the field to comment upon it: their views will be reported in a future issue of this journal. Editor