Asociación entre los subsidios tróficos antropogénicos y la variación de la razón H/L del tiuque (Daptrius chimango)
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Fecha
2023
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es
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Universidad Andrés Bello
Nombre de Curso
Licencia CC
Licencia CC
Resumen
En la naturaleza, es común que ecosistemas más productivos subsidien a otros
menos productivos con el movimiento de recursos, alterando las redes tróficas
locales. Lo mismo ocurre con los subsidios tróficos antropogénicos (STA) que, al
alterar la abundancia, el acceso y la periodicidad de estos recursos alimenticios,
pueden tener efectos (positivos y/o negativos) en distintos ámbitos de los
ecosistemas (desde el nivel del organismo hasta la comunidad). Estos cambios
pueden producir situaciones de estrés sobre el individuo, generando respuestas
neuroendocrinas (cambios en los niveles de catecolaminas y/o glucocorticoides)
para poder hacer frente a estas situaciones. Una de las consecuencias de estos
cambios hormonales son el aumento de heterófilos y la disminución de linfocitos
en la sangre, lo que es posible medir realizando un índice de cuantificación del
perfil de leucocitos, en este caso, la razón H/L. A la fecha, el efecto que poseen
los STA sobre la razón H/L de las aves no ha sido investigado. Las aves
carroñeras son un gremio el cual es común de observar en grandes agrupaciones
alrededor de fuentes de STA, debido a su forma de alimentarse, haciendo este
gremio un grupo modelo ideal para investigar los efectos de los STA. En esta
tesis se evaluó la asociación entre los STA y la razón H/L del Tiuque (Daptrius
chimango). Se esperaba observar un aumento en la razón H/L a medida que
aumentan los STA. Para ello, se calculó la razón H/L de 8 frotis sanguíneos de 5
sitios de muestreo distintos en La Región de Los Ríos (Región XIV), Chile. En
estos sitios se cuantificaron la cantidad de estructuras humanas (fuentes de STA)
dentro de tres buffers de distintos radios (500 m, 1000 m y 2000 m) para así poder
realizar una correlación lineal entre estas estructuras y la razón H/L. No se
observaron correlaciones significativas entre ambas variables. Se concluye que
los STA no representan una fuente de estrés para el Tiuque. Para futuros
estudios se propone incorporar otras fuentes de STA (caletas pesqueras,
vertederos y/o restos agrícolas) con un tamaño muestral adecuado.
In nature, it is common for more productive ecosystems to subsidize less productive ones with the movement of resources, altering local trophic webs. The same applies to anthropogenic trophic subsidies (ATS) which, by altering the abundance, access and periodicity of these food resources, can have effects (both positive and/or negative) on different areas of ecosystems (from the organism to the community level). These changes can produce stressful situations on the individual, prompting neuroendocrine responses (changes in the levels of catecholamines and/or glucocorticoids) to be able to cope with these situations. One of the consequences of these hormonal changes is the increase of heterophiles and the decrease of lymphocytes levels in blood, which can be measured by performing an index of quantification of the leukocyte profile, in this case, the H/L ratio. To date, the effect of ATS on the H/L ratio of birds has not been investigated. Scavenger birds are a guild which is common to observe in large clusters around sources of ATS, due to their feeding habits, making this guild an ideal model group to investigate the effects of ATS. This thesis evaluated the association between the ATS and the H/L ratio of the Chimango Caracara (Daptrius chimango). An increase in the H/L ratio was expected to be observed as ATS increase. To achieve this, the H/L ratio was calculated from 8 blood smears collected at 5 different sampling sites in the Los Ríos Region (XIV Region), Chile. At these sites, the number of human structures (ATS sources) within three buffers of different radii (500 m, 1000 m and 2000 m) was quantified in order to perform a linear correlation between these structures and the H/L ratio. No significant correlations were observed between both variables. It is concluded that ATS do not represent a source of stress for the Chimango Caracara. For future studies, it is proposed to incorporate other sources of ATS (fishing discards, dumps and/or agricultural remains) with an adequate sample size.
In nature, it is common for more productive ecosystems to subsidize less productive ones with the movement of resources, altering local trophic webs. The same applies to anthropogenic trophic subsidies (ATS) which, by altering the abundance, access and periodicity of these food resources, can have effects (both positive and/or negative) on different areas of ecosystems (from the organism to the community level). These changes can produce stressful situations on the individual, prompting neuroendocrine responses (changes in the levels of catecholamines and/or glucocorticoids) to be able to cope with these situations. One of the consequences of these hormonal changes is the increase of heterophiles and the decrease of lymphocytes levels in blood, which can be measured by performing an index of quantification of the leukocyte profile, in this case, the H/L ratio. To date, the effect of ATS on the H/L ratio of birds has not been investigated. Scavenger birds are a guild which is common to observe in large clusters around sources of ATS, due to their feeding habits, making this guild an ideal model group to investigate the effects of ATS. This thesis evaluated the association between the ATS and the H/L ratio of the Chimango Caracara (Daptrius chimango). An increase in the H/L ratio was expected to be observed as ATS increase. To achieve this, the H/L ratio was calculated from 8 blood smears collected at 5 different sampling sites in the Los Ríos Region (XIV Region), Chile. At these sites, the number of human structures (ATS sources) within three buffers of different radii (500 m, 1000 m and 2000 m) was quantified in order to perform a linear correlation between these structures and the H/L ratio. No significant correlations were observed between both variables. It is concluded that ATS do not represent a source of stress for the Chimango Caracara. For future studies, it is proposed to incorporate other sources of ATS (fishing discards, dumps and/or agricultural remains) with an adequate sample size.
Notas
Tesis (Licenciado en Biología)
Palabras clave
Tiuque, Investigaciones, Cadenas de Alimentación (Ecología), Subsidio Trófico Antropogénico