Crecimiento y reproducción del camarón Atya margaritacea (Decapoda: Atyidae) .. En este sentido el crecimiento alométrico ha sido reportado en crustáceos. Características evolutivas de nueva aparición. Los nuevos “diseños” surgen a partir de estructuras ya existentes. Estas novedades evolutivas. El tipo de crecimiento de las especies se determinó mediante un análisis de lo que hace suponer una tendencia hacia el crecimiento alométrico en A. similis.
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Allometric growth in cuban gar Atractosteus tristoechus larvae. Universidad de la Habana. Of the 17 morphometric characters recorded, only six showed isometric growth describing a continuous and gradual change in a very few body characters.
The increase in the length of the head alometrioc snout was positively allometric, but their heights and widths were negatively allometric indicating an elongation of the cephalic region that guarantees an efficient food capture. The allometries obtained with respect crecimkento the head, trunk and tail growth showed a discontinuity and abrupt changes in many of the body sizes and proportions that occur mainly from age 4 This reflects the priorities of a developing organism, when important organs must first be developed to allow feeding and guarantee a better survival of the juveniles.
Fish larvae, allometry, development, growth. The development of fish from fertilisation to sexual maturity is a continuum that is punctuated by developmental events and transitions which may be either gradual and unremarkable or abrupt and quite dramatic Webb During growth, fish larvae often go through very complex processes of morphogenesis and differentiation, including changes in morphometric relationships, physiological changes in muscular and internal organ systems, changes in bone remodeling and changes in behaviour.
This term was coined by Huxley and Teissier and describes the relationships between organism dimensions and changes in the relative proportions of these dimensions with changes in absolute size Goldman et al.
Four different concepts of allometry are distinguished: These patterns of allometric growth reflect morphoanatomical growth priorities in agreement with their importance regarding primary living functions that guarantee an appropriate survival Sala et al.
Ontogenetic allometry can be used in fishery biology and aquaculture to evaluate the developmental plasticity of species Koumoundouros et al. The last decade has wlometrico an increasing interest in allometric growth during early development of fish such as sparids Kout-touki et al. However, studies of this type on gar larvae have not been published.
The early development of Cuban gar and its growth rate during ontogenesis were first described by Comabella et al. Atractosteus tristoechus, a vulnerable and endemic species that inhabits the western region of Cuba, could become a promising candidate for aquaculture, considering its high growth rate and good adaptability to culture conditions.
Our research efforts have targeted larvae development mainly, since the hatchery phase is considered the most critical for the successful production of a species. A previous morphological study made it evident that a differential relative growth occurs in this species. For this reason, the purpose of the present study was to characterise the allometric growth patterns of Cuban gar larvae.
Induction and spawning conditions occurred as was previously described by Comabella et al. Fifteen minutes after release from the female, the spawned adhesive eggs were removed from the pond and placed in a L circular fiberglass tank until hatching h. Experimental design, sampling and measurements.
Generic Guide to New World Scarab Beetles-Scarabaeidae-Dynastinae-Dynastini-Dynastes
After hatching, larvae were distributed in three 15 L circular fiberglass tanks 6. The larvae were fed ad libitum with live Moina three times a day The measurements were taken horizontally or perpendicularly to the axis of the body. The equations were established from regressions performed on log-transformed data, using TL or HL as the independent variable Gisbert ; Gisbert et al.
Di or triphasic growth can be alometricoo by two or three different growth curves, respectively. The X value where the slope changes is called the inflexion point. Inflexion points were determined using iteration procedures according to Snik et al. The x-y data set was sorted according to an increasing X.
Also, t tests were carried out to check whether the vrecimiento coefficients for Xmin Xintermediate and Xintermediate X max differed significantly. The Xintermediate value that resulted in the largest t was defined as the inflexion point. Growth coefficients were compared statistically using a t-test. Two distinct growth phases were detected: Of all the recorded morphometric characters, only six presented isometric growth as a function of total length during the early stages of development Table 1.
However, other body proportions and growth coefficients changed considerably during this period. The head length and width exhibited biphasic growth patterns with inflexion points at A second inflexion point appeared at From that inflexion point The other body heights preanal and postanalhowever, recorded an isometric growth Table 1. The pectoral fins recorded a positive allometric growth from hatching to 8 DAH Finally, the growth in the length of the tail showed the same isometric alometric in the early larvae as did other length characters presented in Table 1.
From hatching to alometfico DAH During the early stage of Atractosteus tristoechus development, all inflexion points lay in a remarkably narrow range of body lengths and ages TL Most functional systems of fish larvae are incompletely differentiated at the moment of hatching Eenennaam et al. A significant morphogenesis occurs during the early development when the larvae need to adequately and timely form somatic and visceral systems, as well as specialised structures for an optimal interaction with the environment Dettlaff et al.
The results obtained in the present study reveal that the aolmetrico proportions of this species change considerably, and many morphological characters present a differential relative growth, indicating times when growth coefficients differ statistically. Punctual and rapid changes inflexion point in relation to TL or HL occur in these characters, rather than a continuous and gradual change. Most of the inflexion points recorded lay in a remarkably narrow range of ages DAH.
The most drastic morphological changes observed in A. The larvae began to feed exogenously but continued to use the yolk reserves that meet the energetic demands of capturing prey.
This transitional period was defined by internal, alometrixo and behavioural changes Comabella et al. The lecithoexotrophic stage is a critical period in larval life due to competition for food and predation Balon ; Coughlin The concurrent development of organs associated with these functions must occur in a mutual balance Osse et al. In the case of the Cuban gar, larval behaviour is crecimienro by periods of resting, while executing corporal undulation movements.
For these reasons, during the larval stage of many fish, muscle development, rather than fin growth, may be a key factor in the creciiento increase in swimming performance Murphy et al. However, Cuban gar larvae are characterised by an almost immobile behaviour, and these corporal oscillatory movements do not allow them to move in the water column.
Crecimiento alométrico en larvas de manjuarí (Atractosteus tristoechus)
Therefore, it was not surprising to find that from 2 DAH onwards, the trunk length growth was almost isometric, similar to the preanal and postanal heights, indicating a constant and proportional growth of this part of the body in relation to total length. Significant morphogenesis and growth processes occur in the trunk region: The trunk growth pattern observed in A.
Regarding the development of the digestive system, Mendoza et al. Histological studies carried out on Cuban gar larvae Comabella et al. When the first exogenous feeding takes place, the alimentary canal is well developed and the stomach is morphologically differentiated into three regions, showing the gastric glands in the fundic area, indicating the genesis of chemical digestion. These results are in agreement with data obtained by Comabella et al.
These results reveal the rapid development of this system and ensure that the essential organs for feeding are developed first. During feeding, when Cuban gar larvae detect a prey item, they twist their entire body into a sinusoidal shape, followed by quick bursts towards the prey, and move their head laterally to place the jaws around the intended prey item Comabella et al.
According to Walkerthese actions are commonly associated with predatory strikes that involve both caudal fin movements to generate an impulse and pectoral fins for maneuvering.
Positive allometric growth was observed in both the pectoral and pelvic fins during the early development of A. The pectoral fins are the first to appear but the last to obtain a full complement of rays Betti et al.
Also, according to Murata et al. In contrast, in more evolved fish, the pelvic fins have a trimming function that reduces pitching and up-ward body displacement during braking. Curiously, the Cuban gar larvae were observed to feed around DAH, however from 8 DAH onwards the pectoral fins recorded an isometric growth. For this reason, the relationship between the growth of these fins and the maneuverability function in favour of an effective swimming for feeding as reported for other fish species remains in doubt for Cuban gar.
On the other hand, the pelvic fins of A. What biological explanation could this pattern have? What high-priority functions do the paired fins have in this species? The other fin involved in the locomotion process is the caudal fin. The inflexion points recorded for these species have been associated with an improvement in swimming capacity. A possible explanation for these allometric growth patterns is a change in swimming style Snik et al.
Klingenberg and Froese recorded, for 17 marine species, a strong positive allometry in the body depth behind the anus, indicating that the posterior part of the body became relatively stouter as the larvae grew. These authors related this pattern to a change in swimming style during larval growth, associated with an increasing importance of the tail region for locomotion. However, in our case, apart from the isometric growth in tail length, a negative allometry was recorded for the caudal peduncle depth, with the same inflexion point recorded for the paired fins.
Thus, it is now necessary to define these characteristics for our species considering the swimming structures. Detailed studies of gar larvae, in combination with research on larval swimming kinematics, combining laboratory and field studies of locomotion behaviour, could explain the growth pattern obtained in our study.
Also, it is not only the development of structures that guarantee the start of active swimming and an efficient assimilation of external food that is necessary, but improved mechanisms for food capture should also exist, such as the cephalic development that takes place during the first days of the Cuban gar larvae. The growth patterns recorded for the head and the snout in this species were positively allometric for length and negatively allometric for width, indicating a lengthening and narrowing of the cephalic region during early development.
Positive allometric growth of the head is a common feature in the early ontogeny of fish like the loricariids Strauss ; Schmidtsturgeons Snik et al.
Ecosistemas y Recursos Agropecuarios
Gisbert and Doroshov and Choo and Liew considered that a rapid growth in head length is probably linked to the development of nervous brainsensory vision and olfactionrespiratory gill alommetrico and filaments and feeding systems. Kolmann and Huber stated that a positive allometry in feeding performance assists predators in overcoming the functional constraints imposed by their prey, and may confer a competitive advantage over isometric ontogenetic trajectories, facilitating access to exclusive trophic resources earlier in life.
In the case of the living gar, predatory behaviour comprises slow overall movements followed by a rapid strike, rather than an active pursuit Kammerer et al. Therefore, the elongation of the Cuban gar larvae snout during growth may optimise the capture of rapid swimming prey such as Moina.
The inflexion points for the head and snout lengths-widths of the Cuban gar larvae were recorded at 6 DAH. Our observations revealed that at 4 DAH the yolk sac was externally absent, indicating its depletion, and that the larvae must switch to exogenous feeding. The presence of a functional food alomdtrico apparatus is then required as an adaptation to the ichthyophage feeding habits of this family.
Given this, it is consistent that nearing the point of yolk sac depletion, external crecimientoo efforts are focused on head elongation in order to complete the most essential apparatus that allows the localisation and uptake of prey of increasing sizes, as a functional priority in fish larvae survival.
Of all the morphometric data evaluated, only the pectoral height showed a reduction in absolute size enantiometry from hatching to 4 DAH due to the reduction of the yolk sac. Data for this character showed a great dispersion and a poor determination coefficient R 2 that was generated by the difference in the shape and length of the yolk sac among individuals. The results of the allometric analyses carried out on Cuban gar larvae for the paired and caudal fins, as well as for the growth of the trunk and cephalic region, make it possible to state the following: